He who without necessity embarks
In many matters, is a fool for slighting
The obvious blessings of a tranquil life.

[ὅστις δὲ πράσσει πολλὰ µὴ πράσσειν παρόν,
µῶρος, παρὸν ζῆν ἡδέως ἀπράγµονα.]

Euripides (485?-406? BC) Greek tragic dramatist

Antiope [Αντιοπη], frag. 193 (TGF, Kannicht) [Amphion] (c. 410 BC) [tr. Wodhall (1809)]
    (Source)

Barnes fragment 104, Musgrave 25. (Source (Greek)). Alternate translation:

Whoever is very active when he may be inactive, is a moron,
when he may live pleasantly keeping clear from politics.
[tr. Will (2015)]

Whoever is overactive when he could relax
is foolish, for he misses out on a pleasant life.
[Source]