Mieli = mind.
Miellyttää = to please and therefore a thing that pleases you is miellyttävä = pleasant.
If something is very pleasant, you probably want to have it, so “minun tekee mieli = I want / I desire it.
A thing without mind is mindless = mieletön, but a person without a mind is called mielipuoli and he probably has to stay in mielisairaala (= mental hospital).
If you have many images in your mind, you have good imagination = mielikuvitus (literally “mental illustration”).