All good advice! 10bpm is a big jump if you can barely play something. 2 or 3 bpm is probably more realistic. I know. It's boring. But that's how it's done.
Also - I love Ed's advice. End on a good note. This is almost IMPOSSIBLE to do. It's like gambling in Vegas. Quit while you're ahead. The problem is - when you're ahead, you want to keep going. Ironically, that's when you lose, get frustrated and end up quitting.
Sooo - practice, and when you start to suck - back the bpm down 10bpm and play it perfectly. Then put the guitar down. You will feel good and motivated when it's time to pick it up again.
This is my advice to you, not necessarily anyone else. Everyone is different. I LOVE sucking and being frustrated to the point of screaming. I've embraced it. I get pissed off and power through it. That's my personality. For those who have a more "fuck you" attitude (like me) - just suck out loud, scream, and suck some more. I've done it enough to know I'll eventually nail it. My inner voice would horrify most people. I say terrible things to myself. But it motivates me to do better.
Some people respond to positive motivation. I seem to respond to self-ridicule. Not saying it's healthy! lol
I'm just sharing my method. Everyone has to practice to suit their personality.