While admitting that Ulster have a mountain to climb to qualify for the knockout stages, Doak stressed that there are still plenty of points on offer.
"The first two games were pretty difficult," he told reporters. "But we've got four games still to go and the potential to pick up 20 points in that.
"Obviously we've got to go away to Toulon and that's going to be a pretty tough ask.
"I suppose after the Tigers it makes it disappointing that we didn't come out better than that. But it's a long season and we'll just have to keep digging in and we've got to pick ourselves up."
Ulster next host Scarlets, who lost to Toulon in their only European game so far this season, in December.