eat one's broccoli
If someone had to choke down something ugly just to get a reward, they've eaten their broccoli.
I had to sit through a 3-hour meeting just to get a raise. I ate my broccoli, and it was a long meeting.
He had to drink a whole bottle of vinegar just to win the contest. He ate his broccoli, and it was sour.
She had to wear a costume for a week just to get a bonus. She ate her broccoli, and it was silly.