Preston North End's players travel to Arbroath on Wednesday for an intense three-day training camp with the Royal Marines.
North End's manager Phil Brown wants his players in peak condition for their opening game of the season against Colchester in a month's time.
"It will test us in terms of our mental capacity as supposed to physical capacity," Brown told the club's official website.
"Everybody comes back and does their pre-season and it's difficult, yes it's difficult psychically, but I think it's more important that you ask the question as early as now, who is up for the challenge and the battle ahead?
"It's going to be a long 10 months and I've said that before, but at the same time it will be an enjoyable 10 months if we have people that are prepared mentally."