Before starting to work out make sure you get a full physical from your doctor and a letter stating it is ok for you to do physical activity. Many gym and aerobic centers will require this before letting you start.
Depending on how long it has been since you last did regular exercise it is recommended that you start off slow and gradually build up your workout to harder levels.
It is generally recommended to start off at the gym with just the treadmill and the lifecycle for the first week or 2. This is to wake the muscles up and to slowly get you prepared for a harder workout.
You will generally want to find a speed on the treadmill that is a pace you can keep up with little discomfort and do it for 20 minutes. After this take a 5 minute break, stretch a little and have a drink of water, then go back and increase the speed just a bit then do another 20.
Remember that pushing yourself too far is taking a gamble that you may not be able to live with. In a casino you can put everything you have on the roulette table and maybe you win and maybe you lose, but in the gym if you push too hard you can die, so take things slowly.
Many people make the...