Adding to the list of household names linked with the franchise, Gary Oldman was originally going to voice General Grievous in Revenge of the Sith. This was all set to happen, but Oldman pulled out after discovering the movie was using non-SAG actors (he was a member). This led to Matthew Wood voicing the role.
Staying fit is certainly a commitment. Besides doing the physical training, there are some other factors to consider, like nutrition