Of all three delights, right now hunting partridge and woodcock in the North Woods of New Hampshire (around Pittsfield) and Maine is my favorite.
You need to be in good shape to do that, and you need a good dog too. I remember one October when we worried that a somewhat overweight cousin would drop dead busting brush in a Maine swamp. Turned pale, could not go on after 7 hours. Forget roads or trails. Wilderness. Hated to let him rest but we figured that to get his corpse out of there we'd have to quarter him like a moose and pack his remains 4 miles out to a dirt road.
He survived, but never re-upped. I love tramping through the swamps and brush and hills of northern Maine. Damn good workout. If you fire three shots in 7 hours, it's good. If you down a bird or two, even better. It's not shopping.
Like Michigan and Minnesota, our North Woods in New England are wonderfully wild.
For fall and winter outdoor fun, first get rid of that fat. It holds you back to a depressing extent. Anybody can easily lose 10 lbs/month by eating rationally and sparingly. If you have excess fat, remember the rule: Whenever you feel hungry, it means that you are beginning to burn fat - not that you need food. Three meals/day is crazy for people with fat. 3 snacks is plenty.
For grouse hunting, mountain hiking, and skiing, you need to work the heck out of your lower body if you want to keep up with the others. Focus on deads and squats, and lower body endurance exercises. Lots of wall-sits for skiers, because that is half of skiing.
We have friends who ski all winter in their 80s. They keep themselves in great shape for it. Working out and eating sparingly year-round. I want to end up like them. Vigorous, wiry, and energetic.
SCIENCE: 
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