As others have said, the top tip is to exercise consistently for the rest of your life. Exercise needs to become an essential part of your weekly routine.
I know a lot of people who decide to get fit, start going to the gym or riding a bike or whatever - for a few weeks or even a few months, maybe a year. They get fitter and then at some point they start to lose interest. 6 months later they are back to doing nothing and they might as well have not bothered in the first place. Don't be that guy.