I've recently come to the conclusion that the single thing that separates successful individuals from unsuccessful one's is the ability to like/enjoy productive activities. Work most noticeably comes to mind.

How and why do we like things?

When I was 16 - 18 I tried numerous times to work out. I'd do it for a couple months and stopped because I wasn't getting anything from it (physically or mentally). Then, when I was 19, everything just clicked. Today, I work out because it's fun. What happened?

There are a few different areas in my life where this happened. What are the common flips that I switched each time? Why can't I recognize those switches in other areas of my life?

Does anyone have any thoughts on this subject?

PS: I'm new here so please be kind to me.