We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
Mountain Climbers are plank position, so they are full body exertions: shoulders, arms, core, legs. And cardio of course.
To do them correctly, knees to elbow, and no humping your back or butt - flat back. No jumping either. A left and right leg counts as one Mountain Climber. Start slow, and do not try 200/day at first unless you are in tough shape. As with the pushups, divide your sets in time but push for the most you can do in one set. If too easy, push the speed.
And don't quit with your pushups. 100/day should be comfortable by now, so maybe go to every other day with them, or vary the type of pushup to reduce the number. I did.