It's not easy. But I can give you some hints, since I'm older than you. (
When you are young, you have the idea that bad things that have happened to others, will not happen to you......wrong. They can and will, but are less likely to do so if you start early in life, to live healthy.
The main thing to remember.....eliminate all risky behaviour, as much as possible. I made mistakes when I was young, and I'm paying for it now. If you're a male, find out about your father's life. If he suffered from something, you are likely to do so......avoid his mistakes. You have also inherited your mother's problems, less of them of course. Keep this in mind.
Here are a few mistakes I made when I was young......
Eating healthy.....maybe the hardest to do. I am diabetic now, so was my father. Keep your weight down, and avoid sweet things at all cost. You can find/make things with sugar substitutes. Do it... Fat stuff is out, lower your red meat input, and don't snack between meals. Almost all snack foods are unhealthy. I'll admit to occasionally breaking the rules. But I try to eat healthy now.....and I regret not doing it when I was young.
Don't smoke....avoid places where others do. My father smoked and died from it. Fortunately I never picked up the habit. If you smoke, turn your life around.....do everything you have to, to stop. Other illegal drugs are obviously out, in a healthy life.
Avoid other risky behaviour.....my mother had arthritis when she was older. I've also got it bad. IMHO.....exercise, but avoid activities that involve high joint impacts. Running is something I always loved...no more. My knees went first, then ankles. Riding a stationary exercise bike is good exercise without the risk of running.
Other risky behaviours.....riding motorcycles. I did it for a long time....even after a badly broken leg. That injury has caused me much grief now that I'm older. Wish I never saw the things.....
SPCR related.....save your hearing. I now have tinittus....caused by loud motorcycles, loud music, power tools without hearing protection, etc. Both my mother and father wore hearing aids. I hope I don't get to that point.
Use your good sense.....things that you do when you are young, will have a much greater effect on you as you grow older. And don't worry, you will grow older. It happens all too quickly.