Cessna 172 pilot reported taxiing to the runway with the nose wheel towbar still attached.

Narrative

I was scheduled for a solo flight to the Practice Area on aircraft X. After completing my preflight inspection; I taxied to the fuel farm to refuel. As part of the normal fueling process; I attached the tow bar to reposition the aircraft. Once the aircraft was moved clear of the fuel area; I went inside to return the fuel card; retrieve my ID; and receive approval for the solo flight.After returning to the aircraft; I believed the tow bar had been removed and began normal engine start and taxi procedures. While holding short in the designated run-up area; the control tower contacted me and reported that the tow bar was still attached to the nose wheel. I immediately stopped the aircraft and notified ground control. Maintenance arrived on site; removed the tow bar; and inspected the aircraft. No apparent damage was found; however; the aircraft was squawked pending review by maintenance management.The probable cause of this incident was an oversight during ground operations following refueling; resulting from a momentary lapse in situational awareness and failure to conduct a final walk around prior to engine start.To mitigate future risk; I will ensure that a complete walk around is always conducted before engine start to confirm all ground equipment; including the tow bar; has been removed. I will also ensure that a wing walker is used any time the aircraft is being repositioned and that the aircraft is properly chocked whenever stationary or left unattended. These actions will help prevent similar oversights and ensure compliance with ground handling safety procedures.