You can do this workout without weights or a gym but if you want to up the intensity, you can add weights. If you don't have weights, you can up the intensity by increasing the work time and decreasing the rest time.
All exercises are done for 20 seconds with a 20 second rest between.
Begin by doing three sets of everything, as you get stronger and fitter or if you are already pretty fit, go with 4 or 5 sets of each exercise.
1. Mountain climbers
2. Press ups (on your knees if you can't do 20 seconds of proper ones with good form) (up the intensity by doing decline, diamond or stability ball press ups)
3. Table chin ups
4. Squats (add weights to up the intensity)
Whole body workout in 5 exercise done in around 10-15 minutes!
I reckon anyone can find 10 minutes out of 1440,
3 times a week!