on one's toes

on (one's) toes

Active, alert, and focused. Having two kids under age five sure keeps me on my toes! This attorney is known for using really deceptive and underhanded tactics, so be on your toes.
See also: on, toe

on one's toes

Alert, ready to act, as in Orchestra players must be on their toes all the time, so as not to miss an entrance. This metaphoric expression probably alludes to boxers or runners who must be on their toes in order to move or start quickly. It gained currency with Richard Rodgers' and Lorenz Hart's extremely popular musical, On Your Toes (1936). [Early 1900s]
See also: on, toe