I agree with what was said earlier, about how keeping in shape isn't about living longer, it's about living better. You don't have to be an endorphin junkie to appreciate being able to DO whatever you want, whenever you want. Pickup game of hockey? Backyard football? Impromptu wrestling match to determine who gets shotgun?

Done. No problem.

Of course, having the stamina to make portages and paddle all day without forcing a layover the next day is a plus, too.

The hard part for a lot of people is finding the time to make fitness a part of their daily life. The answer for me came via bicycle - I'd ride to work or school every now and then, then I'd ride more, then I'd ride for fun, and the next thing I knew, I was logging 2,000+ miles each year, and buying studded tires so I could ride through the winter while my poor pickup just sat in the driveway. I even rigged up a home-built canoe trailer, so I could haul my canoe to the fishing spots without having to drive. I saved a lot of money on fuel costs, and was able to get back into decent shape, and the only thing I had to do was add a little time to my commutes.

Now, my work commute is often in excess of 700 miles, so the bike has become far less practical; and when I'm at work, I can't leave the site to go riding whenever I want. It's like jail, being cooped up in a trailer/lab/office for 30-40 days at a time. So I had to start something different.

I've been amazed at the kind of full-body workout you can get with just a set of dumbbells. I train with high reps + motion for endurance and stamina, as opposed to trying to "bulk up." Using these cheap Wallyworld dumbbells I can work almost every muscle in my body, including the core. Paired with pushups, various lower back / abdominal sets, and a cheap doorway pull-up bar, I can get a great workout without having to make a special trip to a gym, which isn't an option out here anyways. A few hours every day, or every other day depending on laziness, and I'm able to stay in shape while I work without messing up my schedule.

But if you're thinking about getting in shape, my first advice would be to buy a bike. Ride for fun, ride to work, ride to the store. It's a lot easier on the knees than running, and you can make your ride as demanding or as easy as you want. Stop in your local bike shop and ask questions, ride a few different types of bikes, find what you like, and they'll be more than happy to set you up with a bike that will last you many years.

If you want to start a weight regimen, my advice would be to start small. Do pushups and situps at home, just a few here and there, and let your muscles get used to daily demands. Then just keep it up, and start adding reps/sets when you feel ready. Work your way up to using weights - the beauty of dumbbells is you can add or remove weight as you go along.

But the most important thing is: don't stop. You don't have to work out every day, but don't let yourself go without it for too long, or you will find yourself starting over and getting discouraged. The post-workout soreness will go away faster and faster as time goes on, and you'll find yourself having more energy and a better attitude in your daily life.

Just my $0.02