Resistance exercises like lifting free weights and working out on weight machines can improve muscle tone, and add definition to your figure. Weight-training is a good companion to aerobic activities like walking or biking, which burn calories and promote cardiovascular fitness. If you just want to tone up, use a lighter weight, but do more repetitions. To increase muscle mass, you should do sets of eight or fewer repetitions, using a heavier weight. However, don't try to lift more than is comfortable for you; this can cause injury. Also, it's important to rest each muscle group at least 48 hours, before exercising it again. Muscles need time to recover and build after your workout. If you stick to a regular schedule, you may start to see results within a few weeks. You might notice that drooping arms or flabby legs are looking tighter, as stronger muscles keep tissue from sagging. Certain muscles may become more defined, such as the row of stomach muscles sometimes called 'the washboard.' Finally, because muscle weighs more than fat, it's possible you could lose inches, even though your weight stays the same. To find out more about improving your figure through exercise, consult a health care professional.