To overachieve overachieving. Excessive overachieving. Biting off more than you can chew (metaphorically).
Eliana got really over-achievy at UCLA and tried to double major then freaked out when she saw how many classes she had to take in her remaining two years in order to do that. Over-achievy.
Dude: "Hey, John, what do you do for a living?"
John: "Dude, I'm a Dr. / Lawyer!"
Dude: "Whoa. Don't you think that's a little over-achievy of you?"