For the past couple of years or so I experimented with a way to workout without any equipment/space/time, motivated by living in a very small studio apartment while I went to school and was trying to save money (plus I don't like the gym and going outside was kinda gross since I lived in Hollywood for a bit). I went through lots of different routines, with various sets/reps, different bodyweight exercises like pushups and crunches, and simple cardio like jumping jacks and running in place, but ultimately I found that it wasn't about high reps and long durations but more about intensity, so I started to refine the bodyweight exercises and lean towards slower, more intense exercises like elevated pushups, doing very slow negatives, isometric holds for minutes at a time, isotension, and pull ups, but the best discovery above all was an exercise called burpees. These are pretty intense, and even now with how much more in shape I've become by doing them, they still wear me out so much. They also require just enough space to basically lay in. I eventually turned these into tabata burpees, which is a form of interval training that takes a mere 4 minutes. I also experimented with frequency and went from everyday with weekends off, to M-W-F, to finally M-Th, which seems to be just right for me. Thus, I spend about an hour twice a week exercising, and am in the best shape I've ever been and continue to make gains steadily!
My routine is as follows:
- 3x8 elevated pushups (slow negatives [10 seconds], different hand positions each set)
- 3x6 L-pull ups (slow negatives [5 seconds], different grip each set)
- 3 frenchies (w/ 10 second holds)
- various isotension exercises for a couple of minutes
- tabata burpees
Actually I guess I don't use "no" equipment, but my investment has been very minimal: an "Iron Gym" pull up bar ($30) and a tabata timer app (free). There are even websites that have a tabata timer that I used to use. And not only is it cheap, but I can pretty much do it anywhere and with little time commitment (thus no excuse for skipping).