I was invited by some co-workers to be in their volleyball league. A friend of mine was dating a man who seemed like a great catch. He was handsome, physically fit, charming and nice...until we played volleyball with him.
He turned out to be one of those people who took recreational volleyball very seriously. He went ballistic on the sand court, screaming and cursing at people on his team when they missed a shot. He made some of the women cry. He made some of the men cry, too. Everyone dropped out of volleyball that summer.
Business happens in after-work volleyball leagues, bowling leagues, on the golf course, in the racquetball and squash courts, and at the gym or health club. Be a good sport. Congratulate the winners. Compliment them on a good game. Be gracious to the losers. Tell them they were worthy opponents, compliment them on something they did well. Thank them for the game.
The same is true back in the workplace. When you are competing against another person for a promotion and the other person gets the promotion, congratulate that person.