The answer is simple: your loan term will shorten but your monthly payment will stay the same. A number of our customers hope they can reduce their monthly payments through paying extra but no lender will do that.
To lower your monthly payments, you have to refinance your loan. If you haven't considered refinancing your Discover loan yet, you definitely should: not only can you reduce your monthly payments within 2 minutes or less, your total interest expense will go down as well and as a result.