I need help writing a letter of recommendation for grad school!

[EGL0722]

So, one of the professors I've asked to write my letter of recommendation for graduate school (M.S. in SLP) is giving me an interesting assignment: He wants me to write my own recommendation letter (from his perspective) emphasizing all of my strengths; he will then base his letter of recommendation off of that.

The only problem is, I have no idea what to write. Obviously, I've never written a letter like this before. What is included?

Here's what I know off the top of my head (that he knows too):

I received an A+ in his history of Afghanistan class last semester (and I expect nothing less in another class with him this semester -- he's also VERY highly regarded in his field and has worked for several government agencies).

I'm a strong overall student (3.46 GPA at my first school, 3.98 GPA at my second school -- and I'm back at my first school due to a concussion). I'm a hard worker.

I've had eight surgeries due to a heart valve defect (though I've addressed this in my personal statements briefly) and I know what it's like to struggle in rehab, so I can connect with patients.

That's what I know immediately. What else should I include? I want to make sure this letter is amazing (even though I know this professor will write an amazing letter anyway). Help would be appreciated!!