• Think of the flip side: if you're always winning, you're never being challenged. You might as well be playing against children, the outcome would be the same. It's only when you're losing that you can learn something and get better.
• I recommend trying new strategies that you're not sure about, probably guarantee yourself to lose, but try to understand why and whether there is anything useful to incorporate into a different strategy.
• Don't let yourself go into "try-hard" mode until you're sure you can handle a loss like an adult, that's the real win. Until then, force yourself to lose repeatedly to get used to it.
• When a game starts, assume you've already either won or lost based on your current skill level and the luck you'll have during the game, and focus instead on learning something new that will help you to win the next match.
• Lastly, be happy for your opponent just like you would be happy for a friend having good fortune.

These are all skills I had to develop to combat ladder anxiety in SC2, or being sunk in SoT. In SC2, there would be stretches where I would win 10 in a row and feel like I wasted my time because I didn't learn anything. What good is winning 10 times just because my opponents blundered? Not like I have anything to be proud of or to use to win future matches.

"I never lose, I either win or learn." - Nelson Mandela