Ponerse las pilas, ponerse a trabajar duro.

To buckle down.

He'll have to buckle down (to his work) soon if he wants to pass these exams.
Cambridge Dictionary Online.

In Educational materials:

If Don buckles down now, he might be able to graduate from high school this year.
Speak English like an American by Amy Gillett.

In News:

"Coach Woodley says the Bearcats will enter Pershing Arena ready to launch the three and his team will need to buckle down on defense"
Heartland Connection.

"Students buckle down for last days of school."
The Daily Helmsman.