Weight loss suggestions for my cat?

My vet has informed me that my cat needs to lose a few pounds, I know this is in my cat's best interest. He is used to grazing on a food bowl whenever he got hungry but he is now on a strict regimen of 1 1/2 cups per day of his prescription food. He's almost 11 years old and I suppose his lack of exercise because he's getting older has contributed to this, he's very upset that I have taken away his food bowl, I'm having to show some tough love but is there anything else I can do to help his weight loss goal?