Cessna Citation Latitude Captain reported uncommanded aircraft movement when chocks were removed during pre-flight. Aircraft was brought to a stop.

Narrative

When we arrived at the airport I fell when I got out of van landing on my right knee. I got up and my did various tests on my knee. My knees were scrapped and sore but I believed I could walk it off and I'd be alright to fly. When we were ready to depart I asked the FO to pull the chocks because I had abrasions on both knees and I didn't want to kneel on the abrasions while pulling chocks. I was in my seat checking the SID when I heard my FO call out. When I looked up I saw plane was rolling; turned on the AUXILARY HYDRAULIC PUMP and applied the brakes. The plane stopped after rolling about 20 feet. The plane did not injure anyone; strike anything; or leave the ramp surface. We were both shaken by the incident when we got together; I looked at the Crew Alerting System (CAS) messages and there was no yellow LOW BRAKE PRESSURE message. The First Officer then told me that they the realized that they did not set the brakes during the POWER ON CHECKLIST. I did an assessment of what happened and while it was appropriate and allowable for me to ask the FO to pull chocks it was out of the normal flow of operations. I believed that my injury might be affecting my ability to perform as a crewmember more than I thought and might have other unforeseen consequences if we continued. I decided to call in and was assigned duty not including flying in the interest of safety.Suggestions: I believe there was some complacency on my part in two areas. First; I only looked at my ability to operate the controls as the only way that my injury would be a threat to the flight. I feel I underestimated how disrupting normal flows might also be a threat. Second; I am sure I glanced at the CAS when I asked the FO to pull the chocks. I am just as sure when I checked the CAS and I only looked for the amber LOW BRAKE PRESSURE message and did not check for the white PARKING BRAKE ON message. I don't know if it is possible for Garmin to reverse shade the display of the white PARKING BRAKE ON message on the CAS so it has more visibility on the on the display and doesn't get lost in the large number of white messages we have as we prepare to depart. I believe that would make it easier recognize when it is displayed and when it is not displayed.