Jake Kleckner, a former Disney World cast member who worked in Frontierland, said to "expect things to go wrong."
"On any given day, there's thousands of people in the park," he told Business Insider. "Someone is going to do something that's going to wreck your plan."
He said that his family came to visit him and tour the park on Christmas, while he was working at Disney's College Program.
"We went to Hollywood Studios and we did probably almost everything in the park by the time we were done," he said. "And none of it was planned out. I didn't have any of the fast passes planned in advance. I didn't have any dining reservations. We just took the day as it went."
Christina Hartless, a former Disney cast member who worked at Epcot, told Business Insider that it's a good idea to plan everything out in advance because a more "go-with-the-flow Disney vacation is not really completely possible anymore."
But she recommended "taking things in stride" and not getting "too stressed out about the specifics."
"You're on vacation," she told Business Insider. "You're there to enjoy yourself. You don't want to be stressing out about every little thing if it's not going exactly the way you wanted it to. Just kind of live in the moment and enjoy what's going on and what you're doing, even if you're on one side of the park and you're missing a fast pass on the other side."
Kleckner said that guests with type A personalities in particular should not "take yourself or your vacation too seriously."
"Remember to relax and have fun," he said. If you use your time wisely, you will get done everything that you want to get done. You don't have to stress or freak out. Your vacation shouldn't feel like a non-vacation."
Are you a current or former Disney cast member with a story to share? Email acain@businessinsider.com.