You're lying. Otherwise you'd be all-to-eager to help yourself disprove Iacoletti's 'Walt's Fabrications' list
It's not that hard to find -- even for somebody as ignorant as Chapman.
WCR p. 152:
A test was also conducted to determine the time required to walk from the southeast corner of the sixth floor to the second-floor lunchroom by stairway. Special Agent John Howlett of the Secret Service carried a rifle from the southeast corner of the sixth floor along the east aisle to the northeast corner. He placed the rifle on the floor near the site where Oswald’s rifle was actually found after the shooting. Then Howlett walked down the stairway to the second-floor landing and entered the lunchroom. The first test, run at normal walking pace, required 1 minute, 18 seconds; the second test, at a “fast walk” took 1 minute, 14 seconds. The second test followed immediately after the first. The only interval was the time necessary to ride in the elevator from the second to the sixth floor and walk back to the southeast corner. Howlett was not short winded at the end of either test run.