ベストをつくしたら後はくよくよ考えないことさ。

best; vest

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to exhaust; to run out; to devote; to serve (a person); to befriend; to do to exhaustion

later; afterwards; since; future; after one's death; descendant

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

worrying about; moping; brooding over; fretting

to think about; to take into consideration; to ponder; to reflect; to try to come at a conclusion; to think over (something); to intend; to decide (to do); to plan; to come up with; to devise; to scheme; to predict; to anticipate; to expect; to suspect; to doubt; to consider (somebody to be something); to look on

thing; matter; incident; occurrence; event; something serious; trouble; crisis; circumstances; situation; state of affairs; work; business; affair; after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to; nominalizing suffix; pretending to ...; playing make-believe ...; alias; aka; nickname; alternative name; also known as

-ness (nominalizing suffix indicating degree or condition); (sentence end, mainly masc.) indicates assertion; come; come now