BitLife does not give you the best of odds to live that long. Sometimes, the game hands you a terrible hand, and you have to deal with it, and when you reach an older age, you don’t have too many chances to come out on top. There are a few things you can do, though.
Each year you have the opportunity to do so, you need to spend that time going on any of the forms of walking. Ideally, try to go at least for an hour each year. You’ll want to do that, meditation, and go to the gym. Not only does your looks stat go up, but so does your health, only by a little bit. It’s not a huge boost, but it keeps your character active and healthy throughout their life.
You can always modify your diet at any point in the game. Keeping a vegetarian or lighter diet when you reach your 50’s and 60’s is a great way to ensure your character only eat healthier food.
Beyond that, you regularly want to make sure you have enough money to visit the doctor. You can usually gauge how often your character needs to visit them based on their earlier lifestyle and how many visits they already had.
If your health ever starts to become love, try visiting a doctor, exercising, modifying your diet, or seek other forms of medicine.
You also want to ensure every bar for your character is fairly high and green. Smarts is probably the least needed of the three, followed by looks, and happiness, and then health. If you see health or happiness dipping, you want to prioritize spending them boosting them. To boost your happiness, try doing things your character might enjoy, such as reading, spending time with loved ones, with their significant other, or purchasing things they may admire, like a fancy new car.
By keeping all of your green bars up as much as possible and having enough money to visit the doctor when you need to regularly, you should be able to have a long life with your BitLife character. Unfortunately, there’s always the random chance something unforeseeable happens, like getting into a fight with someone and they pull a grenade on you or dying because they have a car run them over.