Harden, who has been on the disabled list since June 12 with a left gluteal muscle strain and threw his first bullpen on Sunday, said he only threw fastballs in his side session on Thursday, but that the ball came out well.
"I'm feeling good," Harden said. "I'm getting to where I wanted to be. I'm getting on top of the ball and staying through it. It's coming out of my hand the way it should."
Harden said the tentative plan is to throw another bullpen on Saturday before going out on a rehab assignment.
"I just can't wait to get out there," said Harden, who is not expected back before the All-Star break. "I want to pitch and do it now, but I need another 'pen and another rehab. But I feel good and I feel strong."