In games and sports there is an obvious winner and a clear loser. When we're the winner it feels triumphant. A great accomplishment. When we're the loser, it can be discouraging.
Life is more complex than wins and losses, but we tend to see our work, goals and family life as such. The boss wasn't crazy about your idea, it feels like a loss. The kids aren't obeying, it feels like you're losing.
Thinking this way can be a slippery slope. Too many losses and we feel like a failure. Try to see low points as learning opportunities. Don't let every bad day make you feel like you lost the Super Bowl, because tomorrow you get to wake up and play again.