If it wasn’t a necessity to keep himself fed without carrying extra weight in rations, Tyson wouldn’t ever bother fishing.
He enjoys the opportunity to meditate that it provides and - depending on the water source - water can help relax him, but Tyson would prefer to simply meditate than fish to meditate; he does understand the appeal though.
Tyson hates to waste time whilst working, so fishing allows him to take a moment for himself - to clear his mind and think over the job - whilst doing something productive.
The other side of this is that Tyson doesn’t care about eating, viewing it as a chore rather than pleasure, so he doesn’t even find it rewarding to provide his own food to cook. It’s a necessity. A need rather than a want.
He likes the idea of fishing in a romanticised way, conceptually, rather than actually wanting to go out and do it.