Instead of letting the money you have languish in checking account (or under your mattress), put it into an interest-earning account, like a money-market account, a certificate of deposit (CD) account, or a 401k. These types of accounts pay a higher rate of interest than normal savings accounts. Ask a professional at your local bank for help placing money in these types of accounts.
Note that these types of accounts may require a minimum balance to start generating interest. They also may require a long-term investment, during which time you will not be able to access your money without paying a penalty.