In the initial phase of your mortgage, the majority of your monthly payments are just applied towards paying down your interest.  Only a small percentage of your payments starting off are applied towards your principle and because of this, only a relatively small amount of equity is built in the first few years (particularly so with longer amortizations).

Choosing a shorter amortization, more frequent payment scheme, or utilizing your prepayment privileges all help reduce the amount of interest you will pay throughout the life of your mortgage.  However, the most effective method to minimize your interest costs is to come into the mortgage transaction with a plan designed to minimize interest costs, maximize principle reduction & prepare for the higher rates of the future.