Do you want to do a Burpee correctly?
To properly execute a burpee, stand straight and then bend forward, placing your hands on the floor in front of your feet. Keeping your legs planted, kick your feet back until you’re in a pushup position, and then quickly jump back to the crouched position. Repeat this exercise for three sets of 10 reps. Common variations include performing one or more pushups when you’re in the pushup position and jumping vertically after you’ve kicked your feet forward to the crouched position.
Other Options Instead of Burpees
If doing the whole down and up movement, instead focus on the push up portion of the burpee. One of the biggest challenges is having the strength to do the pushup. Switch the full burpee with pushups you avoid the jumping which may be a problem with the knees and still using the arm muscles and strengthening your core and challenge yourself to try three sets of 10 reps each.
Mountain climbers are another challenging exercise that you can use as a substitute to burpees. This would cover the part of a burpee when your going from the ground up after the push up portion of workout. Bending down and putting full body on floor may be difficult for you switch to mountain climbers and challenge yourself to do 3 sets of 20 rep each.