This guide contains some general tips to keep your mental stable while playing League Of Legends. This guide isn't designed to rapidly improve your skill level, but to make you play more consistently overall.

NOTE: I am by no means a professional doctor/therapist etc. so you should take this guide with a grain of salt. Only you know what personally works for you.

Why are you playing League Of Legends?
Think about it. Are you playing to improve? Or perhaps you're playing for fun?
Knowing why you play is really important for your mental health. If LoL just makes you upset every time you play, you should take a break. Spamming more soloQ without any incentive isn't ever going to make you happy.
If you're struggling to get any enjoyment from LoL, just quit for 7 days or any other amount of time, even indefinitely. No one is forcing you to play.

Don't get tilted about things you cannot control.
Your jungler fed your laner. Your support stole your kill. Yes, that does suck. But you couldn't do anything about it. So why get frustrated? Even if that play lost you the entire game, there is no need to be upset. Because you should play to improve in the long run, not to win every single game. Try your best to adapt to every scenario in-game.

Physical health
Your body needs energy to function properly. Never play when you are feeling tired, hungry, dehydrated and so on. You will just play on autopilot, if you're not in prime condition. Don't play if you don't feel like playing.
Also, don't stay indoors all the time. Go outside for some exercise every once in a while so your brain gets oxygen.

Turn off chat if you need to.
I personally keep chat on, because it doesn't bother me. However, if you just end up arguing with your team mates most of the time, just turn it off completely. Almost all necessary shotcalling can be done with pings.

Don't expect anything from your team.
Play like you would play with and against bots. Don't expect people to read your mind, or even to have any common sense. These standards are way too high for the LoL community. Almost every game has at least one ******* clearly playing to lose. You just need to accept that fact. I repeat, try to adapt to every different situation you ever encounter.

"No, I don't worry. I tell you, I am a man who believed that I died 20 years ago, and I live like a man who is dead already. I have no fear, whatsoever, of anybody or anything."

Thank you for reading! Please leave some feedback, I'd love to hear your thoughts.