I've been a fitness buff for the last few years of my life, and here are some of the things that I've learned, via my own exercising efforts and my endeavors to involve family and friends in exercise -
1) motivation is key. Recognizing the need to get in shape, or simply having a desire to be healthy, is a good place to start. Don't let it stop there.
2) enjoying the exercise you partake in, or the exercise benefits, goes a long way to helping you achieve your goals. I personally enjoy lifting weights. Picking 'em up, putting 'em down, and doing it again 'til I've completed the set. I simply find it
fun. Crazy, eh?

If you know of something that you truly enjoy, seek it out and
make it a priority. If youre reason for exercising is to be fit or to look good, reinforce those motivations with a new set of snazzy clothes or a regular reading of your heart rate. Find what motivates you and seek to fulfill that desire.
3) have goals that you truly can accomplish. Know the end result you're trying to achieve. If your goal is to do a long hike with a heavy pack, pick mini-goals which will move you towards finishing that hike. If your goal is to have muscular, 18-inch arms, set little milestones along the way that will indicate your successful approach.
4) I like having options. I own some basic exercise equipment - weight plates, a few bars, and a sturdy bench, as well as a heavy punching bag. I also have a gym membership. Finally, I have a dog who loves walking and hiking. Between these 3 basic factors, I've got what I need to stay in shape.
Now, let's talk turkey for a moment. My gym membership costs about $30/month. I use the gym 15-22 times per month, so the money isn't wasted, in my eyes. At the gym, I can use a host of cardio machines, weight machines, and free weights. It also has a pleasant, clean pool, hot tub, sauna, and steam room, which I love.
Walking my dog costs me the price of a leash and some decent shoes, as well as the shopping time of periodically replacing those shoes. That's it, it's a pretty cost-effective exercise, with the added bonuses of a healthier, happy pet and a good relationship with him.
My backyard weight equipment is old, some of it even being from a guy at the dump who was going to throw it away! To buy it new, a decent, moderately priced weight bench would run around $150. The weight set I have, which is a smaller-diameter bar with weight plates that have smaller-diameter holes (read: non-Olympic style weights, but just as heavy!) frequently goes on sale at the local Big 5 or Sports Authority for about $110. It usually comes with a 6-foot barbell, 2 dumbells, 4 collars, and 150 pounds of plates. That means one can load up each dumbell with about 75 pounds of weight, which is fairly heavy for most lifts. So, the total cost of this basic weight set brand new would be less than $300 after tax, if one shops store sales. Shop garage sales and you can find some amazing deals! :thumbup:
Now, offset the cost of staying in shape with the cost of poor health, including hospital stays, medications, doctor visits, etc... one can't prevent all accidents and diseases, but exercise really is a great asset in warding off future problems.
My point? Make a choice to exercise and eat healthily, then find a way to stick to it. There are lots of ways to stay in shape, and lots of reasons to do so. Find out what your exercise values are, weather they be body aesthetics, activity goals, health reasons, are all of 'em, then make a plan to achieve your goals. Then, work that plan (and body!)
Good luck, I'm confident that you can do it :thumbup:
Zack