James Harrison said it’s not a question if he wants to return for one more season with the Steelers.

Rather, it’s going to be if his body cooperates through a six-week training cycle that will determine if he can come back for his 14th and probably final season.

“That’s the guarantee I want,” Harrison said Wednesday in an interview with the Pittsburgh Post-Gazette. “I’m going to start the process of making sure that I can get back to where I need to be so I’m able to give 100 percent. If I’m not able to get back to that point, I’ll do what’s necessary to be fair to my team and myself.”

Harrison, who has one year remaining on a contract that will count $1.5 million against the 2016 salary cap, will be 38 in May. But he missed only one game because of injury last season, played more than 60 percent of the team’s defensive snaps and showed no sign of fatigue in the postseason.

Harrison said he will begin training at Performance Enhancement Professionals in North Scottsdale, Az., with his offseason trainer, Ian Danney, the second week of March. After six weeks, he said he will know if his body is responding and he will be able to come back for one more year.

That would take him right to the start of the Steelers’ offseason training activities.

“I want to get back out there and get to at least six weeks of training and, by the end of that six weeks, feel good, not have any aches and pains,” said Harrison, a five-time Pro Bowl outside linebacker who was the NFL’s defensive player of the year in 2008. “You’ll have the normal soreness, but not having aches and pains and be able to have movements will be the key.

“If I get to that point and I’m feeling good, there’s probably a good chance - no, not probably - I will play.”

Harrison said the toughest part of playing one more season is the preparation. He said offseason training, coupled with the OTAs and training camp, is much more difficult than playing a 16-game schedule.

If he does return in 2016, Harrison will need three sacks to pass Jason Gildon (77) as the Steelers’ all-time sack leader.

“As long as you have the desire to do it, the grind is something you got to work through,” he said. “If I ever lose the desire to want to do something it will show in my work or preparation. If I got to point where I can’t do this, I wouldn’t have done it.”

Curiously, Harrison thought he was at that point following the 2013 season when he decided to retire after one season with the Cincinnati Bengals. The Steelers even held a news conference with Harrison announcing his retirement in September 2014. But, after outside linebacker Jarvis Jones sustained a bad wrist injury three weeks later, the Steelers, with the help of veteran players Troy Polamalu and Ike Taylor, coaxed him into coming back.