For the first time in 2015, Winter Park was buzzing with activity Monday as the Vikings began their offseason workout program.

For now, the workouts are voluntary, but the majority of the 90-man roster showed up to lift weights and watch film with their teammates. The group included new faces such as wide receiver Mike Wallace and cornerback Terrence Newman and familiar ones like defensive end Everson Griffen and tight end Kyle Rudolph.

The group did not, however, include a recently-reinstated running back who may or may not still be disgruntled.

No, Adrian Peterson was not in the building, to the surprise of no one. He rarely attended the voluntary portion of the program in the past, when his relationship with the organization wasn’t strained. He did show up last year to show support for then-rookie head coach Mike Zimmer, but that was out of the ordinary.

So the Vikings went on without him Monday.

During the first two weeks of the offseason program, referred to as Phase One in the collective bargaining agreement, players cannot actually receive coaching on the field. They are, however, permitted to work with the strength and conditioning staff and watch film with coaches. Quarterbacks can throw to uncovered receivers, too.

In two weeks, Phase Two begins and Zimmer and his staff can coach players on the field — with substantial restrictions — during that three-week period.

Phase Three is when the Vikings can practice via organized team activities and a mandatory minicamp, which wraps up the offseason program, from June 16-18.

That minicamp is the only time that Peterson — and the rest of his teammates — are required to report to Winter Park. Peterson can be fined if he chooses to skip that.

Peterson does have a $250,000 workout bonus in his contract that he would forfeit by skipping the offseason program. But according to a league source with access to contract information, Peterson’s bonus is tied only to his participation in OTAs and the minicamp.

So with no financial implications for skipping the start of the voluntary workouts, Peterson chose to do so.