I used to work out 40 minutes now only 4

When I first started the plan I used to exercise on the elliptical machine and boy did I hate that machine. I now do an all body exercise called a “squat thrust”. I dont like this either but I just try and do as many as I can in 4 minutes. Most of the time I dont even make 4 minutes but the first time I did 30 reps and then each time I push myself to do at least 1 more rep. I’m up to 50 reps but I still don’t make it to 4 minutes. I’m exhausted when I finished and my whole body gets the workout. Give it a try.