Stretching
Stretching improves your muscles' range of motion and helps keep them long. That's important because they tend to shorten as you get older, making you creaky and a figure of fun for badly dressed skateboarding teenagers. It's also important because an injury to a tendon or ligament could leave it permanently stretched, which raises the likelihood of a recurrent injury.
Lifting weights
Your back is the best barometer here. If it's bending, shift to a lighter weight and slow down your repetitions.
Momentum to lift weights
Eliminate momentum from your reps by trying some reps at an agonizing slowness. Try going up for two counts and down for four.
Too much, too soon
You start out with the best intentions, spend 40 minutes on the step machine and a barely able to walk the next day, let alone work out. It's human, but still ill-advised. If you're out of shape, increase the time of your workout or the weights you lift by 10 percent per week. No more.
Hydrating
Your body needs water. Carry a big bottle with you and slug at it constantly. It'll help your lose weight. Don't worry too much about the high tech sports drinks. A pinch of salt in the water bottle and as banana before the workout will do the job just as well.
