If a person is always complaining, complaining about life, complaining about the team, complaining about the family, then his (her) life must not be very good, should not be rich enough. The richer the person, the more he knows gratitude, gratitude to the country, gratitude to society, gratitude to the team, gratitude for hurt, gratitude for suffering...
With time, you will come to be thankful for everything about your experience.