If you are doing this for exercise as well as building- I get it. But if not attempting exercise, then why not buy an electric jack hammer? Amazon has them for $150ish.
Even if only needed for this one project, it could be sold for most of the money back when finished.
Then the time and energy better spent doing far more productive exercises for health.
I weigh 200 pounds and am 6 feet tall. I think I need to lose weight. After mining 50 buckets, I lose 6-8 pounds. but then I gain again.
It is a combination of the useful with the pleasant.