Nothing but, Should, Have to, Only, All that remains
Structure
(ただ) + Verb［る］+ のみ + (だ(1))
(ただ) + ［する］Verb + ある(2) + のみ + (だ(1))(1) である
(2) する
(A) のみだ is a formal expression with a bookish nuance, indicating that there is nothing other than (A). With verbs that indicate movement, continuation, or hope (like 願う、祈る、練習、待つ、前進、行く、走る) it is often used to express the only possible course of action, in a way similar to しかない. In this use, するのみ can be replaced with あるのみ for an additional literary feel, without changing the meaning.