Retired at the beginning of 2000 at 52. Spent a year working around the house but missed the oilfield. Started consulting for about 4 months a year and did that for about 4 years before finally giving it up altogether. I decided I liked retirement more than I liked work. The only thing I can say is retire before you are too old to enjoy it.
Retirement doesn't mean that you sit around the house all day watching TV, stagnating and waiting for the grim reaper to make a house call. I'm busy all the time running my tractors at the house or at the farm, volunteer work, gardening or just piddling. What retirement means to me is that I can wake up in the morning, look out the window and say, "To heck with it, I'm going fishing or to the gun club to burn up some ammo, etc." Come to think of it, I haven't done either in a while. Maybe tomorrow .... but I have to spray the pasture and cut the yard so maybe Monday. Oh wait, Monday I have Rotary at lunch and then I said I'd lift and tote stuff for a buddy who has a project. Tuesday I have to cut 5 acres for the local library. Wednesday I'm mowing at the farm. When I come to think of it, retirement is a lot like work only it pays a lot less and there's no time off. I'd recommend it to anybody.