Alert, active, or attentive; on top of things.
keep someone on their toes
To keep someone attentive, active, busy or alert.
on one's toes
Attentive, active, busy or alert.
it takes two to tango
Some things need the active cooperation of two parties; blame is to be…
morning person
A person who wakes up, without difficulty, early each morning and is a…
ball of fire
A person who is especially active, ambitious, hard-working, or high-ac…