The Liverpool forward has only managed six goals so far during this campaign and says that he has not been at his best, although he is determined to rediscover his scoring touch.
Firmino told ESPN Brazil: "It’s been a difficult season for me. We have to be sincere, there’s no lack of hope for improvement. My desire is to evolve and grow every day. There’s no lack of motivation for me.
"I challenge myself a lot. I know that I’m not at my best moment compared to the last few years. I always want to be helping with goals and assists, but that hasn’t been happening unfortunately.
"I don’t give up. I’m always looking to improve to help my team to be better, together with the group. I have to evolve day after day."
Firmino's lack of form has come against the backdrop of a nightmare Premier League title defence for Liverpool, with the Reds now only fighting for a place in the Champions League next season.
He said: "For our team as a whole, the season hasn’t been as good as last year, but we have to find a way to continue.
"Our opponents today have a different look at our team. Of course, they always respected us, but today they retreat very defensively. Sometimes it’s very difficult for us to get in and score goals.
"We have to keep fighting. We have to fight for the qualification to the Champions League through the Premier League."