It hit Marty Mornhinweg one morning on the scale. He was no longer a player. He had injured his knee a few years earlier playing quarterback for the Denver Dynamite of the Arena League. Mornhinweg figured he would return to playing at some point, but had become a coach in the interim.

Then he realized his future in football was wearing a whistle, not a helmet.

“I stepped on the scale and I thought the scale was broken,” Mornhinweg said. “I said, ‘I guess I’m coaching.’ ”

More than two decades have passed and Mornhinweg is still a coach, the new offensive coordinator of the Jets. After 10 seasons running the Eagles’ offense, Mornhinweg moved up the Turnpike to attempt to jumpstart the Jets offense, which was 30th in the NFL last season. He will be on the field today as the Jets begin rookie mini-camp with new quarterback Geno Smith.

It is the latest stop in a football life for the 51-year-old who was born in Oklahoma, became a star high school quarterback in Northern California and won a Super Bowl in his first NFL job in Green Bay.

Mornhinweg became a high school legend at Oak Grove High in San Jose, Calif., in the late ’70s. He once played the second half of a playoff game with a broken ankle. He shattered records and drew recruiting letters from all of the biggest schools in the country.

Then they discovered he was only 5-foot-10 and backed off. His high school offensive coordinator was Mike Holmgren, who would go on to become the head coach of the Packers and Seahawks. Holmgren once compared Mornhinweg with three all-time great quarterbacks he coached — Steve Young, Joe Montana and Brett Favre.

“If [Mornhinweg] had been a little taller,” Holmgren wrote in a Wisconsin newspaper, “he might have been better than all of those guys.”

Instead, Mornhinweg went to Montana where he set 89 offensive records as a four-year starter.

When he graduated with a health and physical education degree in 1985, he took a graduate assistant job, figuring he would get into coaching. But when he was home in the summer the 49ers needed a quarterback for camp. He went and learned from Bill Walsh and Montana, studying the coach as much as the quarterback.