sanguine
Meaning: optimistic, cheery
Usage: Polly reacted to any bad news with a sanguine smile and the chirpy cry, “When life hands you lemons, make lemonade!”
zealous
Meaning: fervent, filled with eagerness in pursuit of something
Usage: If he were any more zealous about getting his promotion, he’d practically live at the office.
felicitous
Meaning: well suited, apt 2. delightful, pleasing
Usage: I spent a felicitous afternoon visiting old friends.
alacrity
Meaning: eagerness, speed
Usage: When the coach asked for volunteers, Maya raised her hand with alacrity.