I lost 300 lp last weekend, dropping out of challenger, so I think I can speak to soloq frustration - what motivates me after all these years of league is you can always queue up and play with people who

a) you know they think you suck

b) you think they suck

And that frustration sort of becomes motivation to prove you're right and they're wrong. Maybe that's just me though idk.

Turn chat off and just play the champs you like and focus on playing and learning the game is probably good generic advice that everyone has heard before but bears repeating. Taking a 5-10 minute break to do something between each game (food, laundry, literally just go take a walk if nothing else to do) is another good one. And ofc if you're not enjoying the game you can just not play it.

lp is temporary