What's your most limited resource? Money? It might feel that way, but the real answer is time. You can earn more money. You can't get more hours or minutes or seconds...or years. The latter — particularly as it relates to compound interest, giving your money time to grow — is just one of the things we dive into with Grant Sabatier, a leader of the "Financial Independence, Retire Early" (FIRE) movement, and author of “Financial Freedom.” In Mailbag, does going to a more expensive college mean more success? Plus: How to tackle crippling credit card debt.