Big company mentality

I'm back at work and sloppy. I am feeling undisciplined and angry at myself for it. At home, I sit down and plow through files and any coordinating I need to do. At work, I feel overwhelmed and suck. If I come in on a Saturday and nobody else is here, I have motivation and accomplish much but knowing I have to be here M-F 8-5:30 just does something to me and I slow down. What is this about? I am SO busy here yet I feel I get nothing done - I just fumble all day. I think it is time to tuck in the shirt, suck in the gut and get the work done for my peace of mind. Am I alone on this? Is this basic human psychology?