When to expect results

You don't need to spend hours a day lifting weights to benefit from strength training. You can see significant improvement in your strength with just two or three 20- or 30-minute strength training sessions a week.

For most healthy adults, the Department of Health and Human Services recommends these exercise guidelines:

• Aerobic activity. Get at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity a week, or a combination of moderate and vigorous activity. The guidelines suggest that you spread out this exercise during the course of a week. Greater amounts of exercise will provide even greater health benefits. But even small amounts of physical activity are helpful. Being active for short periods of time throughout the day can add up to provide health benefits.
• Strength training. Do strength training exercises for all major muscle groups at least two times a week. Aim to do a single set of each exercise, using a weight or resistance level heavy enough to tire your muscles after about 12 to 15 repetitions.

As you incorporate strength training exercises into your fitness routine, you may notice improvement in your strength over time. As your muscle mass increases, you'll likely be able to lift weight more easily and for longer periods of time. If you keep it up, you can continue to increase your strength, even if you're not in shape when you begin.