Your credit history is an important part of your mortgage-seeking process.  By credit history, we mean both your ability and willingness to pay your debts as agreed.  Your credit cards, your line of credit at the bank, and your current or past mortgages are all agreements you enter into with regards to paying on time.  If you do pay on time, your credit, however it is "scored", will be viewed as a number that the banks or other institutions will either look favourably on or not. 
If your credit is good, you will be offered competitive rates and in some cases, more borrowing power.  If your credit is poor, you will be offered much higher rates, and in certain cases, you will not be offered a mortgage at all, from any institution.  
If the banks say no, however, you can still get a mortgage, but it will be at premium, "private" rates.  Private groups and individuals are your last chance to get a mortgage, and if you have been delinquent in your credit repayment in the past, the private sector will charge you higher rates, as well as fees, for providing you likely the last option of borrowing money from them.    
So, in the long run, not paying your credit card and other consumer debt now will affect you in the future - it may even prevent you from buying the largest item in your life, your home.
Always pay your bills on time.  It's worth it.

In our Vancouver, B.C.'s super hot real estate market, many of our clients are starting to ask us what they should do with their variable rate mortgages: lock them in or gamble and see if the rates go much higher. 

It all depends upon your situation: are you planning to stay in your home for the long term, or are you looking to get out of the property you are in for a good return on your initial investment?  

And, depending which sort of variable mortgage you have, the rate you lock in at will usually be higher than the rate you are paying now.

Your negotiating ability with your bank will be largely related to your credit score, so, while you are earning money to pay your mortgage, also ensure you always keep your small amount of bills either paid off or up to date.

It's all a big, connected circle.  Due diligence with your finances ensures you, and therefore your bank, more flexibility when negotiating mortgage rates.  

And, always ensure you ask for the lowest rate they are offering at the time when you are ready to lock in.  It can be negotiated - but you must have some power...back to the due diligence on your credit.  And remember, you are the customer.