The Department of Health and Human Services (HHS) suggests the following minimum 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.
• 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.

You are certainly welcome to add more exercise in than the above, but getting moving is part of the equation for good health!