There are only 2 missions where you are using “Chuck” while on foot. For this particular achievement you will have best chances on the first of these missions. Basically “Rover” the little robot will lead the way. You will have to press buttons when prompted, and to be honest you do have to be particularly quick. If you miss a button press, or don’t press it quick enough, you will see “Chuck” go through the obstacle with hesitation and sometimes he will trip and fall. If this happens you will have to retry. Also on this mission there are traps, such as the Gas that is emitted from the grates on the ground. And also there are sections of electricity that will be in your way. For the Gas simply wait until it stops and then run past the grate. And for the electricity it is best that you jump over them “B button” Some you can just run around, but the majority you will have no choice but to jump over. If you get hit by the GAS, or see “Chuck” being electrocuted, you must restart. The achievement unlocks upon completing the mission flawlessly.