Karate

One low block counts as learned somewhere past the thousandth repetition

The styles diverge: Shotokan, Kyokushin and Shito-ryu each emphasise different things, and Kyokushin is the one with bare-knuckle body contact, so watch a class before signing. Stances and basics are drilled in huge volume, which feels dull early on but is how the sequence of force gets written into the body. How much kata versus sparring you get varies a lot by dojo.