Work to improve your healthspan, not just your lifespan.
Why would you want to live to be 100 years old if your health was poor for the last 30 years of your life? Is it really considered “living” if you can’t do the things you want to do based on physical or mental limitations?
“Healthspan” can be defined as the period of one’s life that one is healthy. Focus on eating the right foods, exercising your mind and body regularly, stretching, breathing, drinking enough water, and getting enough sleep. And just as important as adding positive actions is removing negative ones too. There are things you can limit or avoid doing that can shorten your healthspan such as drinking too much alcohol, smoking, not wearing a seatbelt (if you get into an accident), over consuming food, etc.
Keep these things in mind everyday. Yes, you should enjoy yourself every now and then. And moderation goes a long way. But the more often you treat your current self, the more likely you are actually hurting your future self. Make conscious decisions on if your actions are worth the potential consequences.