Well, that's the way to do it. But, sometimes, people do the best they can with what they have, and if you do it right you can set yourself on a much better financial course.
A mere 20-50 dollars in extra principal can take a lot off the back end of the mortgage as well, and thankfully, that is something I have done from day one.
If I had it to do over, though, I would have looked far harder at the 15 year fixed rate than I did. Instead, I went with the 30 yr with no penalty for early payout, and expect it will have taken 22 years when done (if all goes well).
The other factor is that I bought about two years after a local housing bubble burst, at one third the former selling price of the house.
Frankly, to have done it right, I could have bought a block of 4 townhouses for less than my primary residence, and had I done that instead, would have doubled my initial investment and paid for my house.
Live and learn.
No matter where you start pick a goal and have a plan (and a plan B) and you will get there.