A general rule of thumb is following the Physical Activity Guidelines for Americans3, which is at least 150 minutes of moderate-intensity exercise (3.0 to 5.9 METs) or 75 minutes of vigorous-intensity exercises (6.0 or more METs). Ultimately, though, you should exercise at a MET value you can safely handle. So if you are just stepping into an exercise routine, start with lower-intensity exercises then work up to more intense ones with higher METs.