To make your own routine, first pick a timing scheme. One minute hard with one minute of rest is pretty foolproof; you won’t find yourself cheating the hard parts or rushing through the rest periods. (There are, of course, other options.)
Then, pick a few moves that leave you out of breath. Running in place with high knees is a classic; so are quick side-to-side lunges, jumping jacks, and more. The idea is not to work your muscles so hard you get fatigued and sore, but just to get yourself breathing heavy. Burpees might work well for some folks, but be too strenuous for others. You know yourself! Feel free to swap in an easier movement if you’ve chosen something you can’t quite keep up.
Want some inspiration? We like this no-equipment 30-minute HIIT routine from SELF, this 20-minute routine from FitnessBlender, and this 10-minute version from Group HIIT.