Learning to ride is like reminding your body how to do something it's already fully equipped to do. All you have to do is help it by making it simple, one thing at a time. So, for example, if balance is weak, saddle down so the balls of your feet reach the ground, pedals off, and gently push yourself off on a flattish piece of ground. That's all the body needs to learn to balance automatically. And after that, your body knows, and you're ready to put a pedal on, then two, then the saddle back up.
Road craft takes longer, of course, and the learning never ends. But if it wasn't so, 19 would also be too old to learn to drive.