I've often thought about advice that I would give to my past self, but not long ago Irregular Webcomic asked "What would your younger self say if they could see you now?" That inspired me to think about it.
I think the strongest thing she would say was "I thought you were going to accomplish more." And she might not have the tact yet to avoid saying straight out, "I was better than this in school. What happened to make you so ordinary? How come you've forgotten so much?" She'd surmise "So I guess science wasn't all it's cracked up to be?"
She wouldn't mention the physical shape I'm in, because she had plans to get stronger, and it hadn't occurred to her back then that she wouldn't succeed or that it it would be any effort to maintain fitness. I think she'd compliment me on my hair. It looked terrible back then, and if she hung out for a while I'd probably make her ask "How do you do that?" a few times.
She's disapprove of lots of things, in her naïve idealistic way. She would want to put me back on track. I can remember her helping mentally ill people with resumés and job searches, just because they needed a hand and she was confident in her knowledge. "Let me help you make a plan," she'd say. And she'd know me too well to be fooled by my excuses.
Maybe I'd give her plan a try for a while. But I'm tired of trying to succeed.