If you are thinking of weight training but think that heavy duty weight training might be too hard on your joints, depending upon how old you are and what condition you are in, this could be true. That's why you might be able to benefit from slow rep exercises instead. Weight training that is done slowly and still has controlled and intense movements is going to be a lot easier on your joints, will actually be tougher on your muscles, which will help them grow and it will also add a little cardio benefit as well.
You should get yourself an exercise notebook so you can keep track of your progress. A lot of people forget to do this and they think it's silly but the fact is your body doesn't want to change so keeping track is a good incentive to keep you going. When you start seeing the results down on paper it helps to motivate you.
When you decide on a program to go with on the weight training machine you should try and pick about eight different exercises that are going to work the upper and lower parts of your body. This is the kind of workout you should do at least twice a week with a few special cardo sessions included between those two workout days. Don't alternate the body parts and do a lot of sessions during the week, this is only counter productive. You need to remember that it's not the actual workout that's important, it's the recovery time that you give your body that counts most in building the muscle. If you train every day you do not give your body the time it needs to repair itself and grow new muscle.
You will next need to figure out just how slow you want to perform your eight exercises. With each rep you have a positive portion as well as a negative portion of each exercise. Your first part of the motion is at the start and that is the positive and then returning to the original position is the negative. You should make the time for each portion anywhere from 3 seconds to 10 seconds. In other words each part of a rep should be say about 3 seconds each.
After you have figured out how slow you want your reps to be you should then set the amount of weight that you think you can do for say 10 seconds each half of the rep. It can be less but it should be for longer so that if you know you can hold it 10 seconds then there is no doubt you can do it for less time. When you do start your exercise remember to breathe at all times it does you know good to hold your breath when you are performing your reps.
You should start off by doing 5 to 8 reps of each of your exercise or until you reach that point where you know your muscles cannot take anymore and this is called the muscle failure point. If however, you are able to go past 8 reps then you know right away that you have the weights too light and you will need to adjust until you reach that muscle failure.