Cross Train

Cross training is the concept of including many, and more importantly, a variety of activities in your workout. The added variety works different systems and/or sections and therefore provides a balanced workout. It also keeps you from getting bored and increases the chances of sticking to your program.

Realistically analyze your level of physical fitness and scale the intensity of every workout to levels you can handle. As usual consider consulting a physician before starting a new workout routine.
Make a list of activities available to you and cross out the ones you won't enjoy. For example, although swimming is a wonderful form of exercise, if there isn't a body of water or swimming pool nearby you won't be doing much of it. Or if you don't like to swim, you won't stick to your program, simple as that.
Divide the activities into three broad categories:
* Aerobic exercises are exercises that improve circulation and overall cardiovascular health. Aerobic exercises feature light loads but the movement is repeated many times. Walking, jogging, climbing some stairs are classical examples.
* Strength training is increasing muscle strength and mass throughout the body. It is characterized by large loads lifted for short periods or in small bursts. Most of the weird machines you see in a gym and all the exercises done with free weights are for strength training.
* Flexibility is pretty self explanatory; prevents muscle tissue from getting bundled up and prevents soreness. The stretching exercises will increase flexibility.
Cross training is a concept rather than a program, and it simply means generate a program that includes exercises from all the three categories mentioned above.
As a rule of thumb try to do flexibility work everyday, aerobic exercises three times a week and strength training twice a week. Unless you are coached or are sure you know what you're doing, don't do strength training on consecutive days. If you find that you are overwhelmed, DO NOT reduce the number of times per week you do the exercises, simply reduce the intensity; run three time a week but run slower/less, lift twice a week but lift lighter weights etc.
Keep in mind that not every exercise has to be out of a textbook. Flexibility is as simple as trying to touch your toes. Moving around some furniture or picking up your kids and putting them down 10 times in a row could be some nice strength training. Gardening, trying to do all the chores in one day or dancing are excellent aerobic exercises.

Always make sure you are capable of handling the physical activity you are about to start. You should also consult a doctor, at least to hear his/her opinion.