Someone with a great ambition will EAGERLY do what no one else wants to do.
If you don’t know who to call on, seek out these ambitious people for help.
Put rookies on your roster. Also sign up the seasoned professionals who have preserved the vibrant mentality of rookies.
If they happen to be lethargic about taking up the opportunity (and it’s out of character for them): what do they need? How can they get what they need? They’ll come back into the game once the barrier is removed.