Hiking. I don't try to climb mountains,just get out and move. The fact I have to watch my footing and have a chance of seeing (or at least hearing) wildlife helps distract from the fact exercising sucks.

I use mental tricks as well. I had to bribe myself to get started. "Look there's a trail near that takeout place you like, if you hike you can get takeout!" If I run out of breath due to uphill terrain, I'm not stopping because I can't keep going, it's clearly to look at this neat bird/bug/plant. If I have an off day and need to turn back early, I remind myself that I've already won by getting off the couch.