How do i get my boyfriend to stop trying to persuade me that taking add meds are bad?

I take an add medication to help me remember things that i would normally forget and help me finish tasks I'm normally incapable of finishing. I deserve to be able to achieve success rather than sit on the bench as I was doing otherwise without the meds. It's helped me out a lot in life, yet my boyfriend tells me I need to quit taking it....all the time and I'm clearly sick of it. I don't abuse the drug...only take it as prescribed. Yet, he says things like "I've never heard of an adult having add...you need to get off of that...and what kind of doctor prescribes an adult add med. How do I get him to stop harping on this? W/o being mean?