You can have a tough job on the ground too I know people who are scared of small places Claustrophobic I am glad I am not because I have to get under houses alot sometimes do jobs by myself if it is really tight.
One house I got stuck under when I was trying to get out I got in there ok but there was a bearer I could pull against to get in there, then I got stuck with just my face and arms out on the way out was stuck there for a while until dad found me and pulled me out.
When you get a bit scared it is amazing how much your muscles swell up and you get stuck tighter alot of the times you have to nearly fall asleep to relax enough to get out it has happened to me quite a few times.
My dad used to let me have a day of school if there was ever any low house to work under which was good get out of school and under a house.