Updated 05/08/12 – 8:09 p.m.

CHICAGO (CBS) — Less than a week after he was released from the Rehabilitation Institute of Chicago, following his stroke earlier this year, U.S. Sen. Mark Kirk (R-Ill.) has released a video in which he thanks his doctors, and shows various parts of his intense rehab to learn to walk again.

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In the YouTube video posted on his Senate website, Kirk thanks the doctors, nurses and other staff at the Rehabilitation Institute for their work in helping him achieve that goal, only 15 weeks after his stroke on Jan. 21.

“They have some devious ways of making things more difficult on you,” Kirk adds. “Yesterday, I was wearing a 10-pound weight. They described it as the weight of a baby on your ankle, which really does slow you down.”

Kirk’s office said he released the video not only to share the progress in his recovery, but to thank the people of Illinois for their support.

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Doctors have said Kirk should make a full mental recovery, though they expect him to have limited movement on his left side.

Immediately after the stroke, Kirk had emergency surgery to remove small pieces of his brain that were destroyed by the stroke, and to remove a 4-by-8 inch section of his skull to prevent more serious damage from swelling on his brain.

Kirk began his rehabilitation in mid-February with exercise that included walking on a treadmill.

The senator stutters a few times in the video, but for the most part, speaks clearly and coherently.

The video also shows several stages of his rehabilitation, including different procedures he went through as he learned to walk again.

“One of the more interesting setups they had was a set of wraps around my legs, with silver balls to be all recorded, so a stick figure could be generated on the computer,” Kirk says.

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Dr. James Young, chairman of Rush University Medical Center’s rehabilitation medicine, told CBS 2’s Jim Williams that Kirk was courageous for releasing the video, because it so publicly displays his disabilities.

He has to use a cane and harness to walk, and his speech is not what it was before his stroke.

The weakness on his left side is clear.

“If you’ll notice, when he’s walking, the leg goes out to the side. He’s having a lot of hip weakness here,” Young said. “He may some problems with his sensory feedback, knowing exactly where that leg is.”

After watching the video, Young said he believes Kirk’s recovery will take a long time.

“The physical disabilities that we’re seeing in the video indicate it’s gonna be months, maybe years, before he is, hopefully, fully independent,” Young said.

But Kirk said his progress so far has encouraged to him to a set a goal: a walk up the steps of the U.S. Capitol.

“I’m walking again, leading to my hope to climb the 45 steps that my staff counted from the parking lot to the Senate front door, to fight for the people of Illinois,” Kirk says in the video.

Kirk also thanks the people of Illinois for showing patience as he recovers, and he says he’s looking forward to getting back to work “to vote to spend less and borrow less and tax less to help fix our economy.”

Physicians have said Kirk suffered an ischemic stroke, the most common type. According to the American Stroke Association’s website, ischemic strokes account for about 87 percent of all cases. They are the result of an obstruction within a blood vessel that supplies blood to the brain, caused by fatty deposits in the blood vessels.

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Kirk, a North Shore Republican, was elected to the U.S. Senate in 2010, winning the seat once held by President Barack Obama. Before that, he spent 10 years in the U.S. House.