Been using a Branch chair for ~2 years after having a cheap ikea chair for 1. Definitely notice the difference. You're going to want some adjustability, especially with lumbar support and arm height/ width.
Otherwise, the biggest thing to feel better is just getting up every hour or so to move around. I try to go for a walk/ run once a day since leaving retail and losing 10k steps of physical activity.
By that same token, sit-stand desks are nice if you have the spare budget. Otherwise, just get a nice chair and exercise.
Plus other skills to learn to grow the community center. Fishing, tree-chopping, fighting in dungeons. There's a sense of optimization as you learn, grow, and get access to more tools.
It's slightly more action-y than Animal Crossing, but yeah, still a farm game.