You will not be discriminated against because you take longer to earn your undergrad degree. Protecting your GPA is your highest priority, and if you need more time to achieve competitive grades, that's fine. However, adcomms do like to see that you can carry a heavy load and still achieve great grades. That load need not be all academic. It can include work or family responsibilities, heavy involvement in volunteering or leadership activities, a lot of time in a research lab, or studying for the MCAT. If you are taking a lighter class load, then your list of activities should show that you were busy in other ways, IMO.