Well, im 30 years away (42 now, and expect to work till 72.5), so... but when I worked for the county, the joke was, when you have the retirement party, go ahead and make a calender invite 48 months out for the funeral. Many folks we worked with, only reason to get up was work, and when they stopped doing that, they did nothing.
It doesn't sound like that's your mind set, but it's pretty common for people to just waste away for a few years and be gone. Doesn't really matter if it's golf, fishing, hunting, wood working, gardening, whatever there has to be something to fill that time.
Also, my mom's husband has an addictive personality; so he would go insanely into a hobby, could be pool, fishing, golf, whatever, 4/5 days week, to the point he was better than "average" but could never be better than folks "gifted" in it; and get frustrated and start a new thing. Guess the lesson, even fishing can be work; probably better to fish a couple times a week, shoot skeet once a week, whatever, and have some variety in life.