For the second day of our HIIT challenge, we're going to do a Tabata workout. That's just a fancy way of saying "do as many reps as you can for 20 seconds, rest for 10 seconds, and repeat for 8 rounds (4 minutes)". Complete a full tabata with pushups, rest for 1 minute, then repeat for squats and burpees. I found the pushups the hardest, but don't be afraid to drop to your knees if you need to.
Good luck! 💪