Hasselbeck said he's "strongly leaning towards" playing next season.
The 40-year-old is set to become a free agent this offseason, so it's unclear if he'll look to return to the Colts to remain Andrew Luck's backup, or look for one last opportunity to start.
"I haven't really, I guess, made up my mind completely on it," Hasselbeck said, according to Brady Henderson of 710 ESPN Seattle. "You've got to decide that you'll be ready to go for all the other stuff. It's a commitment. If you're a football player, you start back up April 18. It's a grind. You've got to give it everything you've got, you've got to be all in, you've got to realize there are going to be injuries, it is going to be a physical game, you're going to get hit in the head a bunch."
Hasselbeck was forced into action in 2015 when Luck was lost for over half the season due to shoulder and abdominal injuries.
He went 5-3 in his eight starts, keeping the Colts' playoff hopes alive, but left consecutive games toward the end of the year after suffering neck, shoulder, and rib injuries.
Despite the ailments, Hasslbeck said he enjoyed starting for the first time since 2012.
"It was great. It was fun," he said. "I felt awesome actually for probably the first four or five games. It was just a blast to be in the huddle again. I had a lot of fun."
With a weak quarterback free-agent market, it's possible a team will sign Hasselbeck as a short-term solution following his success in 2015.