Edit-On mobile so please forgive the formatting/lack of anecdotal examples.

The training to not freeze up either in the door or combat started early on in the paratroopers training. Flight was still a relatively new concept and the militarization of parachuting had begun in the last decade. The selection process to become a paratrooper involved many events that would help self-select those who “froze” in stressful/dangerous situations. For the stress inducing events, soldiers were taught to place their hands on the outside of the plane door as to prevent them from resisting a “gentle” nudge from the soldier behind them as the goal of the parachutist was to land as close to one another as possible; for every second spent waiting in the aircraft was another hundred feet plus of distance between jumpers. Add that over a stick of 13 and the first and last soldier become a quarter mile apart which is a large distance on the battlefield.

For the stress inducing events, these events included jumping from a 34 foot and 250 foot tower before even completing the first parachute jump from a plane at 1,200 feet. After 5 jumps, the soldier would become parachutist qualified. There wasn’t too much more jump training with most soldiers jumping less than a dozen times (for training and combat) for the entire war.

By D-Day, only one regiment of the 6 US paratrooper regiments was combat tested (505th PIR)-the rest were untested and had spent the last few months training in England for the invasion. The other 5, (501, 502 & 506 {101st} and the 507th & 508th {82nd}) had some combat veterans but not to the extent that the regiments could be considered combat tested. With that in mind, the experience and culture of these units would see most many jump. In fact there are stories of pilots being threatened to turn around after missing the drop zone on the first attempt. Before the jump, some regimental and Battalion commanders issued orders that anyone who boarded an aircraft was to jump or they would be charged with desertion under fire-a charge punishable by death.

For those that were scared to jump especially under fire, the stick (load of paratroopers) was organized in a way that soldiers went as a group as opposed to an individual. Stacked closely together, the stick jumped from the airplane with as little distance and time between the individual members as possible. Thus, there was minimal time to actually think/stop as the soldier behind was pushing the one in front of him. If a jumper did manage to freeze, the last man in the stick was responsible for helping to push him/the mass of bodies. These individuals were normally selected for their size & strength specifically for that purpose.

Finally, it was much safer to be on the ground than in the plane. For the 506th specifically, the regiment suffered more casualties on the jump than in the first three days of combat.

That being said, there are multiple reports of cowardice within the jump/upon landing as these soldiers are not immune to the realities of human nature. While most accounts do not identify them by name, stories of taking a nap are found in more than one source in different units.

Sources: Koskimaki, George. D-Day with the Screaming Eagles Bando, Mark. The 101st Airborne in Normandy Webster, Daniel. Parachute Infantry

I'm trying to figure out how anyone got away with not jumping. My experience was that you had two people that made sure everyone got off the plane after the equipment check was passed. The Jump Master, who stood at the door controlling the exit. The other was the last man in the stick, the pusher, who is a senior NCO or Officer. I have seen Jump Masters literally kick people in the ass to get them out the door if they hesitated too long. So how did they not jump?