What keeps YOU motivated to swim?

I was at work yesterday and got asked an unusual question: How do I stay motivated to swim hours a day, every day, year after year? I told the person that I would get back to them while I mulled over the answer. I thought back to this forum and suspect that most of the folks here compete and the competition motivates them. Me, I don’t compete, in fact, I only know how to swim one stroke, at one speed, never stopping. I guess that I just like to swim and be alone for a couple of hours every day with my own thoughts. While that works for me, I doubt it will prove useful for many others. So, how about the rest of you: What motivates you to keep swimming? Swan