Ready to roll
Definition 1 of 2
Pro Tip 1/3Informal Energy
Used in casual settings to express enthusiasm and readiness. 
When the teacher asked who was ready to volunteer, Susan said, 'I'm ready to roll!'
Pro Tip 2/3Not Literally Rolling
Though it suggests movement, it's often used metaphorically to indicate readiness. 
The band wasn't literally rolling anywhere, but they were ready to roll with the concert.
Pro Tip 3/3Initiative Context
It implies taking initiative or a leading role in starting something. 
When the group project was announced, Mike was immediately ready to roll.