to exert oneself

• 使劲！

  Go for it!

• 使劲跑

  run as fast as one can

• 使劲划桨

  row with all one's might

• 使劲干活

  put one's back into one's work

• 使劲敲桌子

  bang the table vigorously

• 你使劲地拉呀！

  Pull as hard as you can!

• 不能使这么大劲。

  You shouldn't try so hard.

• 再使一把劲

  make one more push

• 马怎么使劲也没有把车拉动。

  As hard as it tried the horse couldn't move the cart.