Lunges are a fantastic lower body exercise (and the one I'm most likely to skip!). There are several ways to do them but it seems the most popular way is to is step forward into a lunge. However, reverse lunges may be preferable for a host of reasons. Stepping back instead of forward is easier on the knees and also makes it easier to retain your balance. Plus, reverse lunges forces your front leg (the stationary one) to work throughout the entire exercise, meaning more gains! Use the same movement pattern as a traditional lunge but step back instead of forward. A wider stance where the knees are bent at 90 degrees at full range is ideal.