I'm looking for a verb that means "to make something productive" or "useful".
Example: If someone is wasting their time by doing something that's not productive, I might say "Spend your time [more] productively".
In the above sentence, I want to replace "spend productively" with a single word, so the new sentence would be "____ your time" where ___ is the word I'm looking for.
Is there a word (verb) that fits the above description?