I think some of the rush in fishing is gambling addiction. You just never know when that big hit might come, and that uncertainty makes you want it more....just one more pass, just one more day, because the only certainty is you won't catch that fish of your life if you don't have gear in the water.
[a motivational psychology study on rats showed that if a rat pushes a lever once and gets a pellet, they will eat until full and then stop. If they get a pellet for every 10 pushes, same, they'll push the lever enough to get full. But if they randomly give a pellet, sometimes every push, sometimes every 10th, sometimes every 100th, then some rats will frantically push the lever non-stop, even if they aren't hungry and instead of sleeping or doing other normal rat things....sound familiar?

]
But yeah, being out on the water, being away from busy life, and drinking beer at normally inappropriate hours all contribute to the fun too.
Best bet is to have happyretirees attitude, that just being out there is the goal and a reward in itself, and catching a fish is a bonus...otherwise you can get jaded and bitter when things are slow.