When it comes to no-equipment exercises, it’s best to subscribe to the Navy’s KISS principle—Keep it simple, stupid. Straightforward, compound moves that hit all the major muscle groups don’t have to be overly complex. In fact, bodyweight workouts should be less about reinventing the wheel and more about sound programming. ReebokONE trainer Maillard Howell points out that with the right equipment-free workout, you can spike your heart rate quickly, boosting your metabolism while improving both cardiovascular and muscular health. Plus, circuit-style routines can be completed quickly, offering stellar results in a modest amount of time. The next time you can’t hit the gym, try this eight-move circuit from Howell—perform each exercise back-to-back as described, cycling through the routine three to four times.