James Harrison is 38 years old and about to enter his 15th season in the NFL. The Pittsburgh Steelers fearsome linebacker has doled out 567 tackles and 81.5 sacks over his career, hits that not only take a toll on the opponents he’s pile-driven to the ground, but also on Harrison’s body. Yet the man still goes through more difficult and insane workouts than even the fittest 25-year-old would dare attempt.

The latest example? Wearing the same gray, team-issued Steelers sweatsuit he always wears, Harrison pushed a sled with an absurd 1,395 pounds on it 5 yards across an outdoor turf. Drenched in sweat, Harrison can be heard audibly grunting as he approaches the finish line with what amounts to half the weight of a mid-sized sedan.

Harrison, who turns 39 on Thursday, continues to embrace his body even as he ages. “#Oldmanstrength,” he writes in the video’s caption, noting that he might add eight plates to the 31 found on the sled in the video so he can push 39 plates to celebrate his birthday. If and when that happens, we will find ourselves in awe once again.

READ MORE:

• The Reason Why James Harrison Wears the Same Gray Sweatsuit When He Works Out
• James Harrison’s Core Workout Looks Outrageously Difficult
• James Harrison Does Push-Ups With a 300-Pound Lineman On His Back