Alacrity

Alacrity: With alacrity (exclusively used with the preposition with) means enthusiastically, cheerfully, eagerly. Alacrity shares its etymology with the musical term for a lively, cheerful tempo: allegro.

She did all this with a frenetic alacrity, as if her mind had to make up for her body's inactivity.

A Book for Today: Serena by Ron Rash

They knew that tone and obeyed with alacrity, leaving me alone with him.