kept one's mind on (verb) buckle down: work very hard
Sinonime: aggressive,
audacious,
bold, challenging, contumacious,
daring, gutsy,
insolent, insubmissive,
insubordinate, mutinous,
obstinate,
provocative, rebellious,
recalcitrant,
reckless, refractory,
resistant, resistive,
sassy*,
truculentAntonime: acquiescent,
obedient,
respectful,
submissive, submitting, subordinating