overkill
overstrive
chase rainbows
overchallenge
kill
kill oneself
lay on
overshoot
exaggerate
swing for the fences
overdo
mismotivate
tax
overcook
shoot for the stars
give
overcommit
whore
overurge
push it
overreach
push
tug
drive
go mad
labour
labor
overcontribute
cook someone's goose
overdose
run someone ragged
bust ass
not give much for someone's chances
underachieve
push against an open door
carry coals to Newcastle
overguesstimate
undershoot
use a sledgehammer to crack a nut
overexpand
overply
underchallenge
fly too close to the sun
chase pennies with dollars
overcompensate
outshine
make an effort
overassist
buck
ettle