WASHINGTON -- Pain was almost a constant part of Bryce Harper's 2013 season. Multiple encounters with outfield walls -- among other incidents -- left him banged up and bruised.

So when the 21-year-old realized recently that he was able to run and hit without pain, it served as an encouraging sign for his third Major League season.

"To be able to hit with no pain and run with no pain was a lot of fun," Harper said on Saturday during NatsFest. "I haven't hit with no pain for about a year, so it's not very fun to go through for a year, year and a half. I know you're going to have your ups and downs, play through pain, but that was something I didn't like doing, and it didn't feel very good. So being able to hit, being able to run, being able to chuck baseballs and things like that, it's been a great offseason. It's a lot of fun to be able to do it not hurt."

Harper sidestepped questions about an exact timetable for his recovery from October surgery to repair the bursa in his left knee, but he did say that he is rehabbing three times a week, day and night.

Manager Matt Williams said that Harper is "on track in his rehab" and added that his main goal is to get Harper ready for Opening Day, making Spring Training a time to balance rest with sufficient at-bats.

"If he goes out there and plays six innings, we don't know how he's going to react," Williams said. "So we'll have to evaluate that every day. But the challenge is making sure we get him enough [at-bats] so he's ready to go."

Harper hit .274/.368/.486 with 20 home runs and 58 RBIs in 118 games last season but slowed considerably after a hot April. He hurt the left knee crashing into the outfield wall at Dodger Stadium on May 13 and later aggravated the injury, eventually spending more than a month on the disabled list.

Williams doesn't want to curb Harper's aggressiveness, but he does hope to channel it better.

"He's going to run into walls. It's going to happen," Williams said. "But luckily, they're padded, and I just hope he doesn't damage the stadium when he does. But he has to play the way he plays. You can't take his aggressiveness away from him, because he's always played that way.

"So what we need to do is maybe be a little smarter, position him in a spot where he can get to a ball, where he doesn't have to run into a wall, or get him to the fence and let him find it to be able to make a play. So that's our objective as a staff. But I'm not going to put a harness on him and say, 'You can't do that,' because that's the way he plays. We'll do some things in Spring Training that will help him get to a point where he feels more comfortable."

Harper plans to spend a lot of time in Spring Training strengthening his lower body while also making sure he doesn't rush the process.

"It's all about how I feel in rehab and how I feel that day," Harper said of his availability at the beginning of the spring. "If I'm not feeling very well, if the knee's not reacting very well, then I'll take a day off and see where I'm at the next day."