Vikings left guard Charlie Johnson left Winter Park on Thursday as a young man, flew home to Durant, Okla., woke up Friday morning and grew old.

Happy birthday, Charlie. Welcome to life in the NFL as a 30-something.

"No doubt you're definitely evaluated differently," Vikings 31-year-old linebacker Chad Greenway said during this week's voluntary minicamp. "It's the old NFL adage. Once you turn 30, they try to get rid of you every day. You just got to keep giving them reasons not to. The NFL is a big machine, and it's going to spit you out when it wants to. I'm just trying to fight against that as long as I can."

Like all NFL teams, the Vikings prefer to thin their over-30 herd to a small group. Johnson is the ninth Viking on the roster to reach 30.

He's also only the fifth projected starter, joining Greenway, receiver Greg Jennings (30), defensive end Brian Robison (31) and quarterback Matt Cassel (31).

Recently, Raiders 31-year-old defensive end Justin Tuck made headlines when he complained that the NFL's free-agent market was disrespectful to productive players in their 30s. Tuck was willing to give the Giants what he considered a considerable discount to re-sign following an 11-sack season. When they declined, he signed with the Raiders.

Meanwhile, in Minnesota, the perception is the Vikings made a couple of sound business decisions to spend the bulk of their allotted defensive line salary cap dollars on 25-year-old Linval Joseph and 26-year-old Everson Griffen rather than 33-year-old Kevin Williams and 32-year-old Jared Allen.

So far, not even Allen's decision to stay within the NFC North and sign with a Bears team ecstatic to acquire his seven-year streak of double-digit sacks has altered the assumption that the Vikings' youth movement made sense.

"With changes in the [collective bargaining agreement], it's been seen that the older players are getting restructured, getting cut, getting released maybe a year or two before maybe they normally would," Greenway said. "As a player, you've got to keep fighting against that and go out and make as much hay as you can while you're playing."

Greenway speaks from experience. Soon after playing through a broken wrist to tie Scott Studwell's team record of six consecutive seasons of leading the Vikings in tackles, Greenway risked being released — a la Antoine Winfield last spring — if he didn't restructure the five-year, $40 million deal he signed in 2011.

In return for a guarantee of his base pay for this season, Greenway accepted a pay cut of $1 million to $5.5 million. So, essentially, he's on a one-year, prove-it deal considering next year's $7 million base salary can be wiped from the salary cap if Greenway is released.

"At first, your reaction is like anybody's would be," Greenway said. "I don't care what you do. When somebody asks you that kind of question, initially your response is just like Justin [Tuck] said.

"I feel like I've given so much to this community and this organization and this team and fought through so many injuries and played.

"The reality is you got to think about your family first. I think the best decision for my family was to remain here, where we're rooted and take a deal that was good for my family and good for the organization. And play basically this year out."

Also resisting the urge to "feel anointed" as a veteran over 30 helped Greenway deal with the business side while sweating through a voluntary minicamp at the end of April.

"When I come to work, I'm not going to sloth around," Greenway said. "It's just not me."

Meanwhile, Johnson awaits a Friday evening surprise birthday party he says he's not supposed to know about.

He also made it through minicamp without being presented a cake and 30 candles.

"In all honesty," he said, "I'm not sure anyone knows Friday is the big day."

This is the NFL, Charlie. Everyone knows.