All that is needed, of course, is regular conditioning.
Aerobic and weights, endurance. The body is a healing
machine, but it's best sustaining repairs are performed
over long, un-interrupted periods of time which
exist where it doesn't have to focus its healing on
one or two nagging injuries. This is a complex
subject, but you all know what I mean.
This is why you have KG saying he's like to sit out a year.
KG sitting out a year is not a loss for him, because
in all likelihood, doing so would actually ADD another
entire year onto his career length.