Wiktionary
oversanguine
a. Too sanguine; overconfident, too disposed to hopes of success.
Usage examples of "oversanguine".
Overdepressed in defeat, as oversanguine in victory, the King of the Franks ordered the catapults and mangonels he had brought to the siege of Arques dismantled, and retired to seclusion to put his mind in order and recast his shattered plans.
Suppose you are by nature rather oversanguine or overdespondent, and you make no genuine attempt to evolve that nature into poise.