And I do find when swimming all my daily cares vanish. My mind relaxes and that can be a wonderful time for ideas to be generated. I find as long as I write those ideas down on getting home I don't forget them again.
Thinking time is important for your characters too. Someone like my Eileen has to think ahead given her role as a fairy godmother fighting evil all the time. She needs to work out the best way of using her magical powers so she gains the most advantages from them. It's not just a question of pointing her wand and going "zap"!
Conflict fuels stories but that can include inner conflict as a character works out how best to solve a problem. It's even better when that character gets it wrong (and realistic too given nobody gets it right all the time so your characters shouldn't either).
Also given Eileen's tendency to drop herself right in it with her cousin, the Fairy Queen, and her Council, it also pays Eileen to think ahead about how she is going to handle the latest fall out from her actions. And she needs as much thinking time as possible for that!