The 35-year-old Keisel played out the final season of a five-year contract for the only team he's ever known and spent the offseason training, hoping for an opportunity to prolong his career.
That chance came last week when the Steelers re-signed the long-time veteran in an effort to bolster a reconfigured defensive line that has struggled through three preseason games.
''The unknown is hard and there were times when I was like `well I don't know what's going to happen, it might be over for me,'' Keisel said. ''There were also a lot of times when I felt like I still could play and something was going to happen.
''That's what kept me focused, more the positive than the negative, and that's why I think I'm here right now.''
It's a relief for the Steelers' fan favorite, who is known for his thick, bushy beard. He was just glad to be back with the team that drafted him in the seventh round in 2002.
''It's great to be back in the locker room, it's great to be around my teammates, it's great to just come to work,'' Keisel said. ''I enjoy the drive to work from my house, going through the city and seeing the sights. Just knowing that I have work to do is a great feeling.''
The Steelers initially parted ways with Keisel in the offseason, opting for a youth movement along the defensive line by drafting Stephon Tuitt in the second round and signing 27-year-old Cam Thomas as a free agent.
They decided to add experience to that depth last week, bringing the two-time Super Bowl winner back for his 13th season with the team after he agreed to a two-year, $3 million deal that included a $500,000 signing bonus.
Keisel said he doesn't know where he'll fit in yet, but he could start opposite Cam Heyward on Dick LeBeau's 3-4 defensive scheme.
''I'm going to go out there and I plan on playing,'' said Keisel, who earned $4.9 million last year. ''Whether that's starting or whatever they want, I'm going to earn my role on this team and where that is at is yet to be determined.''
Keisel traveled to Philadelphia with the team on Thursday but did not play. He watched on the sideline as the Eagles' first-team offense had little trouble with the Steelers, piling up 251 yards and three scores in a half.
It wasn't much better during the other two preseason games as the first-team defense gave up a 73-yard touchdown run in the opener against the New York Giants and let the Buffalo starters roll up 212 yards in the second game. It's a disturbing trend for a defense that finished 13th in total yards and 21st against the run.
''If you can't shut down the run, you're going to have a long day,'' Keisel said. ''You have to have pride in what you do. You have to have pride in yourself as a defense and a front.''
Keisel, who will turn 36 next month, missed four games with a foot injury in 2013. But he was still effective overall, finishing with four sacks, a forced fumble and two recoveries. He said he's anxious to get started and wants to play in Thursday's preseason finale at home against Carolina.
''I really tried to make sure I was ready when my number was called,'' Keisel said. ''I was getting after it, but it's a lot different going against my shadow than a 350-pound guard. Those are things I can't really simulate.
''There are certain things you can do to train, but really, until you play the game, you're not going to be in the type of shape you need to be a good, consistent player.''
The Steelers expect Keisel to round into form, serving as the experienced, veteran anchor he's been the past 12 seasons along the defensive line.
''I think he brings a sense of pride, a sense of what this team has been and wants the best for us no matter what the situation is,'' Heyward said. ''He's a brother and he's one guy I can always count on no matter what.''
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