Siebers recommends using a heavy enough weight to feel resistance, but not strain or pain. Your individual body will determine just how much that is, and you should err on the light side at first; five pounds may not seem like a lot, but it's better to be conservative than suffer.
And how much should you work out? According to the American College of Sports Medicine guidelines, beginners should do at least two days per week of any type of strength-training exercise. Your workout should consist of 8 to 12 repetitions each of 8 to 10 different exercises working all the major muscle groups -- chest, back, shoulders, arms, abdominals, and legs. (A repetition is how many times you lift the weight, pull the rubber tubing, do a pushup, or whatever.)
Machines or Free Weights?
Both free weights and weight machines work well, and experts say there's no evidence that one is superior to the other, so this is largely a matter of choice.
Machines are a good idea for people who are overweight and/or out of condition, since the exercises are generally done seated and with back support, Seibers says.
But if machines are not an option, investing a few dollars in a set of light dumbbells and/or some resistance tubing can give you what you need to start toning those muscles.
Whichever option you choose, keep your moves basic at first, the experts say. For the arms and upper body, try these exercises:
* Chest presses
* Reverse flies for the back
* Overhead presses for the shoulders
* Bicep curls
* Triceps kickbacks or extensions
For the lower body, don't start out with squats and lunges, which can put too much impact on weak joints. Instead, try:
* Quadriceps extensions for the front of the thigh.
* Hamstrings curl for the back of the thigh.
* Side-lying or standing leg lifts to work the inner and outer thigh.
And don't forget to work on strengthening your "core" muscles -- the ones in your abdominal and lower back area. Core stability is key to avoiding injury, according to Carver. "Somebody with strong upper extremities but no core stability can hurt themselves doing a bicep curl, for example, if they can't stabilize the trunk," she says.
You'll also avoid injuries -- and get the best results -- by varying your workouts. For example, if you work the biceps, back and legs one day, work the triceps, chest and shoulders the next time you train, Siebers says. Alternating between muscle groups gives the ones you worked plenty of time to recover.
Incorporating stretching in your strength program will also help keep injuries at bay, says Carver. Most important, don't push too hard. Carver always cautions people that "feeling some discomfort in the muscle is OK, but feeling it in the joint is not."
If you have a health condition or previous injury, you may need to do modified versions of certain exercises or skip them altogether, she says. That's when it's especially important to work with a fitness trainer.
Staying With the Program
Success comes from structure and constant support, according to Siebers. "Calendar it up," she suggests: Chart your week of exercise out in advance so you know exactly what you're expecting of yourself.
Having a friend to train with is one of the best ways to stick to a program, Siebers says, even if he or she is a cyber-pal.
"Internet chat rooms and support groups really help to motivate," she says. "There are a million people out there in your same situation getting online every night and encouraging each other. People need that day-to-day hand-holding."
But perhaps the most important things you need for a successful strength training program -- or for successful weight loss -- are patience and acceptance, she says.
"The problem is, people look too far down the road trying to see the big picture too quickly," she says. "You have to try to accept and love yourself today and know that each day, you're going to get better."