Coming Back From Injuries

There's a lot of people who have been away from jiu-jitsu for non-injury reasons unless you've had children right. What do you think are some realistic expectations for those types to have when they come back to training so they're not physical? There's nothing lost i mean the more time you take off but if you might take time off and still be athletic and and physical it definitely is not going to take too much of a step back.