Before they catch touchdowns, before they take down opposing quarterbacks and before they can even step between the white lines on game day to the roar of thousands packing the stands at Arrowhead Stadium, the players must prepare.
For the Kansas City Chiefs, those preparations for the 2016 season have already started.
The players reported on April 18 for the start of Phase One of the offseason program, which consisted of weight lifting and conditioning and lasted for two weeks.
One of the key men in charge of getting the players ready for the season and throughout each of the phases of the offseason is head strength and conditioning coach Barry Rubin, who is entering his fourth year with the team.
"It's awesome having all the guys back here," Rubin explained. "They're working extremely hard and doing a great job and doing exactly what we're asking them to do. They've been very, very compliant.
"There has been a lot of energy and a lot of effort."
Just this past Monday, the players began Phase Two of the offseason program, which will last for the next three weeks.
Phase Two workouts include individual player instruction and drills on the field, as well as team practice conducted on a "separates" basis. There is no live contact or team offense versus team defense.
"Each Phase builds on the other," Rubin explained of the three phases of the offseason. "We start off Phase One, it's moderately hard, but it's getting you ready for Phase Two, which we're in now, and that's getting you ready for Phase Three, which is coming up in a few weeks."
Chiefs players and Chiefs Strength Coaches working out on Thursday.
During Phase Three, the Chiefs will conduct a total of 10 days of organized team activities (OTAs). No live contact is allowed, but seven-on-seven, nine-on-seven and 11-on-11 drills are permitted.
The Chiefs OTAs will take place May 24-26, May 31, June 1-2 and June 7-10, and their mandatory veteran minicamp is June 14-16.
The communication between the strength staff and the coaching staff is crucial during this part of the offseason, when players are lifting and conditioning as well as going through their on-field workouts during the day.
"Everything is very organized," Rubin explained. "The days they run hard with the coaches are the days we reduce the volume, and vice versa.
"The communication between us is really good and that's obviously important."
As Rubin enters his 20th year in the NFL, he understands that with new technology, drills, equipment, workouts and techniques, the program is always evolving.
"Each year we try to bring something a little different and a little better to the table from the previous year," he said. "It's just small tweaks that we make. We try researching things and see what's the latest and greatest, and if it's really something we realistically can do, and is good, then we'll put it in our program."
Rubin is one of the many guys behind the scenes who deserves credit for the work he puts forth in getting these guys ready to play every year, and watching and helping these guys develop are what he prides himself on as a coach.
"Seeing them grow and get better, that's probably the best thing," Rubin said. "We have a great bunch of guys. We really do. This is a special bunch and coach Reid, he's the best. He's awesome to work for because he backs us to the fullest.
"He brings good guys in here and he demands good things out of them."
Rubin can already tell a difference with the younger players through just a couple of weeks of workouts.
"You can definitely see improvement," he said. "They're understanding the role of the strength and conditioning part. They're trying to make the most out of it, and when they do that, you can see them improve."
The players have returned to One Arrowhead Drive for Phase One of offseason workouts
It's not just the guys wearing the jerseys that Rubin has taken to helping develop, either. He does that with his staff as well.
Just this past offseason, former assistant strength and conditioning coach Brent Salazar, who had worked with Rubin for the past few years in Kansas City, was named the head strength and conditioning coach of the Minnesota Vikings.
Salazar had been with the Chiefs since 2007.
"I've been fortunate to have a lot of great strength coaches that have worked with me," Rubin explained. "It's always good to see when they move up and I'm always excited for them. That would be my goal for every strength coach that I have is for them to move up.
"I do take pride and I love when they go off and become a head strength coach somewhere, but that's all them. It's not me."
With Salazar moving on to the Vikings, that provided an opportunity for a couple of guys to move up and bring on a new face as well.
Here's what Rubin had to say about the three guys on his staff:
"(Assistant strength and conditioning coach) [Travis Crittenden] has been with me since day one here in Kansas City, and he was with me in Philadelphia," Rubin explained. "He's just an awesome coach and awesome human being. He's very positive and has a lot of good energy. Very knowledgeable and a great weightlifter himself. He looks the part. He's such a loyal friend and coach. The guys like him a lot. I'm very fortunate and happy to have him.
"We brought in Ryan Reynolds from UCLA. He's another awesome strength coach. Extremely smart. Extremely good. He's had a lot of experience with a lot of the sports science equipment and he knows them and has a great feel for them. He has a great feel for what's realistic and what really can help us. He's an outstanding coach and an outstanding person. So he's been a great fit for us. He has come in and done an excellent job. So we're excited about him.
"We moved up Devin Woodhouse, who has been with me for a couple years now. He's another very loyal person and extremely hard worker. I feel very blessed and very fortunate to have those guys with me on our strength and conditioning team.
"The great thing I like about all three of those guys is that they're all positive, they bring a lot of energy and will work their butt off to try to help out guys."
Everyone is working towards the same goal, and each player challenges each other to be better. It doesn't matter whether it's fighting back from a 1-5 record to start to the season or simply competing to finish first in a 20-yard sprint.
"When you compete, it brings out the best in you. That's what we do."