"There is no question that I need to step up because he's gone," the 31-year-old Lee said, via the Dallas Morning News.
"I think it's a responsibility for me, similar to how it was for Jason Witten. Jason kind of set the tone for us. Not only did he set the pace leadership-wise, but he also knew that you had to pass the leadership down and you had to be gracious and try to help guys. That's something I am really trying to do also. If you want to have a great team, the leaders got to bring guys in. You can lead by example, but you've also got to get the young guys working the right way too."
One key aspect of being a leader is availability to a team. Witten, after all, went 14 consecutive years without missing a game while Lee has missed 24 contests over the last four seasons.
"It's unacceptable how much time I've missed. I got to stay on the football field," Lee said earlier this offseason, via The Dallas Morning News.
Lee recorded 101 tackles and one interception in 11 games last season. He missed five games due to hamstring issues.
Witten retired from the NFL and joined ESPN as an analyst for Monday Night Football.
Had Witten returned for a 16th season, he would have been the longest-tenured player in franchise history. As it stands, Witten is the franchise leader in games played (239), receptions (1,152) and receiving yards (12,448). He is third in receiving touchdowns (68) and tied with Hall of Famer Bob Lilly for the franchise mark with 11 Pro Bowl selections.