Practice :) You're never too old to learn anything. If you don't have a bike, rent one. The way I learned was that it's easier to go down a slight hill without your feet on the ground than it is on a flat surface. Try to find an area where there is a small slope that ends in the ground being flat. This way, you can practice going down the slope with your feet off the ground (not necessarily on the pedals) and then turn quickly to begin going up the slope. It's easier to attempt to pedal when you have a bit of momentum and are going up a hill. Hopefully that made sense. Whatever your strategy is, if you keep at it you will be able to ride a bike in no time.