Back in the late 90s when I was taking out my first mortgage as a graduate, I went to the bank and asked for a mortgage. I was on reasonable money as a graduate working in IT, and set my sights fairly low - i.e., my eventual mortgage was just over twice my salary, as I had a bit of a deposit. I was on my own then, as hadn't yet moved in my wife-to-be, so it was jus try salary that was taken into account at the time.
When trying to sort out the mortgage with the advisor, he said, and I quote "Borrow as much as you can for as long as you can". He was "advising" me to take out a mortgage for nearly seven times my salary, as opposed to the just over twice that I went for. Of course, he could see the money coming in from extra fees/commission if I took his advice....
Now, was sticking with a low mortgage a good idea, financially? I don't know the answer to that as I haven't sat down and worked it out. But what I do know is that me having a very small mortgage enabled me to pay it off relatively quickly, do more fun "stuff" (lots of foreign travel) and generally speaking not worry about my mortgage at all. Since paying it off, my wife and I were able to buy other properties to rent out, thus getting an income, and not having to be in debt to finance it.
But, if I had taken his advice I'd possibly now be living in a bigger house as, with the benefit of hindsight, I now earn more than I did when I took the mortgage out and interest rates stayed low - but I didn't know this when I took the mortgage out; no one did. If interest rates had gone up a lot and I had taken out a much bigger mortgage, I'd have struggled to make the payments early on - I am convinced of this.
I also take on any 0% finance deals that are offered for things I need - cars, TV, etc - and I always pay them off in full with no fees. I don't take out loans for stuff that I don't need, but only things that I was going to buy anyway, and only ever take out a loan if I can get more from investing that money elsewhere. Seems to work for me as I like to keep the capital in the bank, and earn some interest, even though the rates here in the UK are pitifully low.