Witten is dealing with a lacerated spleen sustained in the preseason opener.
"I'm doing all right. ... Stay optimistic. Take it one day at a time. Get healthy and regroup when we get back to Dallas," Witten said Thursday. "Obviously I would be hard pressed thinking I am not out there for the Giants game. Again, there is no timetable."
The seven-time Pro Bowler got hurt in the preseason opener Monday night when he got hit after he caught a pass from a scrambling Tony Romo.
Witten is expected to miss the rest of the preseason for the Cowboys, starting with Saturday night's game at San Diego. The regular-season opener is Sept. 5 at the defending Super Bowl champion New York Giants.
The Cowboys have said the best way for Witten to heal is to stay as inactive as possible.
"It's hard. Think about sitting in that hotel room when your team is working," Witten said. "It's a challenge but ultimately that is the best thing you can do for your team and yourself. Plenty of guys here to pick up the slack so that's not a concern. For me, it's get healthy as quick as you can."
Witten said the pain is similar to having a broken rib and isn't too bad though he can "feel it in there.'
Doctors will reassess Witten next week.
Witten has missed only one game in his nine NFL seasons, because of a broken jaw when he was a rookie. He said the spleen is different than any other football injury he has ever had.
"Absolutely and that's what is difficult, the challenge in a situation like this. Rest is the only answer," Witten said. "I am learning. I will be a better football player because of it. There is no question. I am thankful it happened now in preseason and not later when I would have had to miss games."