There are a few classic ways to increase your faith that everyone mentions. I'll go over those first, and then I'll give you another longer thing to think about that is probably new to everyone reading this the first time.
Romans 10:17 declares
So then faith cometh by hearing, and hearing by the word of God.
If you have no other means of developing faith, read the Bible. Start with the gospels and Acts, but don't forget about the Old Testament. There are many mighty works of God recorded there as well. Note that when this quote to the Roman church was written, the Old Testament was all they had to go on. As you see how God cares for His people when they follow Him and read the promises that He has made, and know that He is unchanging, it can build your faith if you are one of His children.
A second means of building faith is taking part in testimony services. They are rare anymore and sometimes only found in discussions in small groups. A member of my Sunday School class testified of two things this week when we were talking about the miracles of Christ having to do with nature. In the first case, she related the story she was told when young about another class member who was out riding his bike with a friend late in the evening when it was nearing dark. He wasn't supposed to be out past dusk, but he'd gotten a flat tire on his bike when he was still two to three miles from home. He prayed and God put air in his flat tire and he was able to peddle his bike home. In the other instance, two ladies at a Bible study group that this lady was at shared a story about a prairie fire that happened northeast of town. As the fire was burning up the hill pushed by the wind towards their subdivision, both of the ladies prayed for God's help and the fire split and went around their two properties, leaving them unharmed. Why did He answer that prayer when there are so many other disasters that happen? Maybe it was because He knew that one day what had happened would be shared and posted in this web article for someone to read whose faith was shaky or non-existent. If that person is you, then you now have to decide what to do about a God that is still working miracles in this day and age.
The third means of building faith is personal. Remember the things that God has already done for you. Perhaps it is just salvation, but perhaps it is many other things. My family was driving down the road with a newly licensed driver at the wheel at night on the interstate going the speed limit which in my state I think was 75 at the time in a SUV that had a rollover risk. There was a big rock in the road and she swerved around it and put the vehicle into a spin that ended up being 540 degrees. But we stayed on the road, we didn't tip over, and nobody was coming from behind but what we could get our wits together, figure out what was wrong that the SUV wouldn't start again after the spin, and get started back down the road before anyone hit us. We've had a miracle of healing as well, which was instantaneous and for something that the doctors couldn't fix as well and which really helped someone's quality of life. We also had our own encounter with fire. A wildfire was burning up the backside of the hill that forms the edge of the subdivision where my mother lives threatening around 140 homes. The fire department had closed the road, but we were helping get her things and her to safety while they worked to try to stop the fire. We were all praying as well, of course. The fire stopped before reaching mom's house. The house across the street and up a couple of houses had its garage catch on fire due to the wildfire, so it stopped close, but it did stop before causing damage to my mom's home or other homes in the area. So we have things to build our faith on and perhaps you can read these and they will help build your faith as well.
But what do you do about other big things: cancer, heart disease, strokes, paralysis, antibiotic resistant bacteria, tornadoes, hurricanes, fires, the really big scary things that the statistics are known about and which for some at least, man can't really do anything about?
I'd like you to think about this. It may not help, but it may. I grew up with science fiction. I enjoyed the various TV shows and movies of the last 50 years. If it was good science fiction, I probably watched it. Even if it was bad science fiction, I probably watched it. I remember the holodecks. You walked into a room and the computer ran a program, and there you were in a virtual reality environment that you could sense with all your senses that seemed completely real and you stayed there till you said the command to get the exit to the deck to appear. The person that created the AI scenario had complete control over what happened. Today, pilots train in VR environments. They aren't quite as cool, but they can introduce any problem or environmental condition or ground forces to attack or fighter jets that attack you. Computers have come a long way.
When I was growing up, board games were all we had. My war games were board games from Avalon Hill (now Multi-Man Publishing). Today there are first person shooter games on the computer or TV console that are increasingly realistic. The VR environments only the big defense contractors or the government could afford when I was in college are now available to people playing multi-player games world wide (not with cool controls like a wrap around cockpit, but with much greater reach). The VR effects are on their way to simulate the wrap around cockpit as well. The programmers designing the games have complete control over what the characters can do. If they get a certain token, maybe they can walk on walls. If they're a medic, maybe they can touch a man that is wounded and give him his health back. If they decide something isn't playing correctly or is too strong a weapon or too weak a weapon, they can simply push an update out and presto - things change in everyone's "reality" worldwide.
What I want everyone who is struggling with faith to realize is that for God, our physical reality is just as easy to manipulate as the virtual reality of the gaming systems or simulators of today is for the programmers of the companies who designed them. God spoke the universe into existence. It isn't any harder for Him to "push an update out" that raises someone from the dead or heals someone or causes a hurricane to go away than it is for the programmers to fix their VR worlds. Probably lots easier, in fact.
God won't always grant all our desires. We need to be in tune with the Holy Spirit in order to know the mind of God for any given situation. At some point everyone will die unless the rapture happens first (Enoch and Elijah notwithstanding whose time will come). And God knows what the best time is for each, even if we are saddened by a passing. But sometimes God intervenes even in raising someone from the dead. We just need to give Him the glory for anything that He does for us. But we really need to grasp the concept that regardless of how hard anything might be for man (or how impossible it might be for man), it is nothing for God to alter our reality to something different if it suits His will.
Faith is a hard thing to build. The doctors have developed so many statistical models for cancer, for example, that they can lay out just what your chances are for any particular cancer of any particular size for any course of treatment you can name and give you the odds you will be alive in six months, a year, five years, ten years based on exactly what you do. God doesn't care about the odds. If He chooses to heal you, He will, and you'll be fine. If He chooses not to, then you'll need to take your chances with the doctor. Seek and know His will for any situation, and then have faith that He can make any change He wants to make. Just give Him the glory for what He has done and pass the word to the world. They need to hear that He is still at work, He still loves His people, and He is still on the throne in Heaven!