Without regular exercise, both muscular strength and cardiorespiratory efficiency could begin to decline and accelerate the aging process. The biggest challenges during this decade are that your career will be taking off and if you haven’t already, you may be starting a family. This is why finding a favorite mode of exercise in your 20s is so important: It will be a regular habit built into your schedule and routine by the time family and career start making more demands on your time. Exercise is so important during this time that if you haven’t been successful at following a regular exercise program on your own, you may want to consider hiring a personal trainer or going to a studio with instructor-led workouts.

If you have a demanding schedule, it’s important to realize that even 15 to 20 minutes of exercise at a time can make a big difference and provide significant health benefits.

As you progress through your 30s, you will want to make smarter nutrition choices and plan on going to bed earlier because the right diet combined with proper amounts of sleep are essential for good health.

Without regular exercise, cardiorespiratory efficiency—the ability to efficiently move oxygen around the body—starts to decline, which can increase the risk of developing heart disease.

Without any regular physical activity that challenges the muscles to do physical work, by the time you reach your mid-30s, you could start to experience a loss of muscle mass.

If you’re a man, as you reach the later years of this decade, not only will you experience lower levels of testosterone, but if you have excessive amounts of abdominal fat, it could convert what testosterone (T) you do produce into estradiol, a female sex hormone that can promote the growth of breast tissue.

Both strength training, to increase muscle mass, and metabolic conditioning for weight loss are extremely important in this time of life. Both men and women should do strength training because it can elevate levels of human growth hormone (HGH), which can metabolize fat, promote muscle growth, and help skin maintain a youthful appearance.

Core strength training workouts that challenge your muscles to work to the point of fatigue can provide significant benefits if they are performed at least 2 or 3 times a week.

Metabolic conditioning workouts that leave you almost breathless are important at least 2 or 3 times a week to help ensure optimal function and performance of the cardiorespiratory system. It is also important to make time for walking at least 10 to 15 minutes at a time 2 to 3 times a day (ideally, once in the morning and once during the workday) for overall health benefits.