Time has a way of warping when you are not looking. Blink, and you'll soon realize that years have gone by, as you struggle with work, paying bills, and just making ends meet. But as you get older, you need to be more careful about these large lapses in time. And without proper care, the body will quickly degrade if not kept in shape, as can be seen by America's expanding waistline and the fact that the U.S. Obesity Epidemic Continues to Grow.
We'll see if I caught mine in time, but for now at least I can begin the process of getting back in shape. Towards that goal, we recently completed setting up a home gym.
Why set up your own home gym? Why not just join a local fitness center? Well, for me, my biggest constraint is time, and so having a gym at home really pays for itself when you consider the overhead of travel to and from a fitness center. Also, as I learn more about what is involved in fitness and proper exercises, I have found that most local fitness centers just do not have the right types of equipment there to be worth my time and money. And I really shouldn't have to mention awful music, OPS (Other People's Sweat), and hefty fees commonly found at the local fitness centers.
A good guide on how to set up your own home gym, with pointers to proper equipment and possible vendors, can be found here in the September 1, 2002 issue of the CrossFit Journal. Our current home gym is a first-pass at their prescribed configuration, and includes a multi-station exercise center, plates and dumbbells (and a couple kettlebells), treadmill, striking dummies/bags, pullup station, and some tumbling matts. There are a few pieces of equipment I am lacking, such as a climbing rope, rings, and a rowing machine, but for the most part the current configuration allows for a reasonably effective and useful workout.
Note that the above-linked CrossFit Journal article also contains a list of things you can do to get kicked out of your local gym (I think they were being humorous) - maybe that's a way to get your gym to refund the remaining balance of your gym membership if you want out?
Day 1
Bring your own music - use a boom box - and turn it up to inspiration levels and start working out. ACDC's "Thunderstruck" should do the trick.
As for how to structure your exercise workouts, I can't think of a better program than CrossFit - there you'll find a WoD (workout of the day), videos on how to do each exercise, nutrition information, and lots more. They stress functional fitness, and their workouts will help you get into the best shape of your life.

If you want more of a tactical workout, then you might want to try The Pit Workout
and The Pit Workout - CrossPit. I am currently working through The Pit Workout and, well, let me just say it's not yoga down at the Y or tae-bo. Once I get The Pit Workout under my belt, I'll move to CrossPit.

Finally, if you need some motivation to get back in shape, whether you stick with your fitness center or build a home gym, and want examples of how effective the CrossFit program is, you may want to watch this video of one of the CrossFit workouts.
Note that setting up this gym completes one task of my 101 Goals in 1001 Days project.