"The frustration comes from when we're not winning and the offence isn't moving the ball. It has nothing to do [with] me. It's about I want to win. I've got a nice contract. I've been to Pro Bowls. I've made all-Pro. I want to win. Sometimes, the formula may go to me. But sometimes, whatever is best for the team, that's what we need to do," Marshall told reporters.
"So I'm always going to be frustrated when our offence isn't No. 1 in the league. I'm always going to be frustrated when we're losing. So yeah, I'm frustrated. We just lost two in a row.
"I try to just focus on what I can control. There's times where it might be third down where I might be doing some chip blocking to help out the offensive line. I've just got to hang my hat on [the idea] that we're doing what's best for the team. There's some times where I'm running some routes to pull the coverage."
However, Marshall has admitted that it was "tough" to have large spells out of the game and reveals that he has been trying to improve his reaction to not being targeted.
"It's really tough. I'm not going to lie to you. Like I said last week after the game, my No. 1 goal going into the work week was to work on my body language when I'm not in the game. It's been like that the first few weeks, and I kind of let myself down and the guys around me with my body language," he added.
"So I got better at that today. They took me out the game, and that's one positive for myself, just try to keep my head up and keep myself ready for when I'm available for the team whenever they call my number I just try to be there because if you beat yourself up too much or you get too down or too frustrated at the play calling or coverage, the ball comes your way and you drop it.
"So I'm proud of myself today. Sorry for patting myself on the back, but there's not too much that I can hang my hat on today. We lost. I got shut out."
The Bears began the season with three wins on the bounce, but now have a record of 3-2 following yesterday's defeat to the unbeaten Saints.