In my inbox this morning:
Hey Mr. Shah!!
I just wanted to tell you that I’m taking Calculus this year and I have to say, it is just not as fun as it was last year. My teacher doesn’t have fun pictures and she writes on a CHALK BOARD *gasp*. I miss our class! Hope you’re having an awesome year so far.
She’s not the only one who misses our class. This just made my week. Seriously.
Continuous Everywhere but Differentiable Nowhere 
Just goes to show that no matter how bad you think you’re doing, you’re still touching kids.
What a great note! A number of years ago I started a “Roses” folder in my file cabinet (not my idea, but I don’t remember who suggested it) where I began filing notes like this and other positive feedback I got. Now, particularly when I am feeling pretty useless, I take it out and peruse it for 15 minutes or so. By the time I slide it back into the cabinet I am ready to tackle anything.
Love it! I do something similar…
Some blog years ago suggested making a “Feel Good” folder for emails. In it I have emails with really beautiful or sincere thank yous or accolades (rare, but lovely when they come), but also random things that remind me what great teacher friends and funny students I have. Anything that will make me smile when I read it.
It doesn’t have a lot in it yet, but it’s slowly growing. :)
I also keep a file in my filing cabinet for “nostalgia” (like comics that students have drawn on the back of tests, that made me laugh, and thank you cards, and other random things).