Tabata like cardio. 20 seconds really intense, 10 to 15 seconds stop, then back for more. I HATE HATE cardio so it's the only kind that interests me or i'll die of boredom and not do any. Elite athletes do it which i am definitely not one, but i find it makes a difference. You can do any exercise you choose, but i do 5, burpees, bodyweight squats, jumping jacks, mountain climbers, then a kettlebell swing. I'm up to 3 sets so it takes about 9 minutes total (sometimes i go for more than 20 seconds intense). I'm dead after it all.
Gonna try that!