The reason I can run for more than twenty years is not that I have a strong will. It just suits me.
In Haruki's words:
"To tell the truth, I don't even think there's that much correlation between my running every day and whether or not I have a strong will. I think I've been able to run for more than twenty years for a simple reason: It suits me."
Long-distance running suits his personality. The noncompetitiveness, the contemplative nature of running (#52.1), and the desire to spend time alone all suit his personality.
This makes me think about my love for basketball. The social nature of playing basketball (always need to communicate and collaborate), the quick feedback loop (good shot or not), the flexibility to train alone, and even "bromance" (playing with friends and making new friends). That's how basketball suits me.
What's the sport that suits you? If you have yet to find one, remember Haruki started running at 33!