keep/lose your temper
keep (one's) temper
To refrain from becoming angered, enraged, or upset due to some provocation; to maintain control of one's composure despite being angry or upset. You're a good driver, but if you don't do a better job of keeping your temper when other drivers make mistakes, you're going to end up causing a crash some day. It's hard to keep my temper with the kids after being kept awake by them all night long.
lose (one's) temper
To become angered, enraged, or upset due to some provocation; to have an outburst upon losing one's patience. I'm usually a pretty calm person, but whenever I start driving, I find I lose my temper at the slightest inconvenience. When we were kids, my dad lost his temper a lot, but he's mellowed out since then.