Have your bicycle ready to ride. Have your clothing, gear, whatever, ready to go. When the moment hits you, all you need to do is get dressed, air up, water in bottles plus a little snack and GO. Chances are good that if you really enjoy bicycling, once you start rolling that special feeling will resonate throughout your being and the motivation to continue starts to grow. No need to go fast or far, just go and enjoy.

I am also an introvert, but have no need for company to make a 20 mile ride or a 100+ mile ride enjoyable. We are all different, and many here have given ideas about getting motivated, your job now is to pick-up the ball and run, walk or ride with it.

Good luck.