Life is too short to sit around and hold grudges; It doesn't make any sense to do it.
Kobe Bryant, is a basketball player who is go down as one of the lengendary players in the game of basketball. One thing we can learn from him, is that he is a LION. He never gives up, he never gives in. He never waste a single time doing things don't improve his game, like complaining or holding grudges.
He is always practising, thinking of winning, planning his next move, improving and keeping at his best.
I think that's what we should or aspire to be. The best version of ourselves. There is no time to sit around and hold grudges. Life is not perfect, life is unfair. However, you can seek to improve the state of your life by starting with the mindset of not complaining, and working hard WHENEVER YOU CAN.