Something I have been doing that has improved my endurance during my training is so simple that I'm wondering if it's actually helping or merely a placebo effect. Calf raises! I don't do them with weights but I do it on an uneven platform. I take the cushions off my couch and stand on it so its very shaky so I have to work on my balance as well as doing the exercise and I swear so far it has helped greatly. Anyone else tried doing exercises like this but not in a routine way?