Very relaxed.....almost comatose. I remember pre-qualifying prior to home shopping. I was told what kind of mortgage I could afford at the upper limits. While my income could have covered the total, I wouldn't have anything left for the "little things" like food, heat, or gas to get back and forth to work. Why impose that kind of stress upon yourself?
Plus, if you're married and both of you have jobs, they assume neither of you will ever lose your jobs, or decide to go part-time/quit to raise kids etc.