Lock oneself in a broom closet and devote every ounce of your energy towards proving results at the absolute fringes of modern math (with the very real prospect of a nothingburger result for 4+ years of work) and suddenly one starts to crave the simplicity of manual labor with immediately tangible results. I knew an ecology grad student whose thesis involved manually tagging hundreds of hours of video of worms moving around on leaves and after she handed in her thesis she walked into the Canadian wilderness and basically dropped off the grid.