Welcome! You may want to try walking to the gym if it's possible. I don't know how far it is, but I used to do that in college and it was the little extra before and after a good workout.
You can (and will!) learn to make little changes with or without your boyfriend's support. There will always be someone out there offering treats (and they rarely offer healthy food)
A great way to get both of you involved is to cook together! Then you can invest in your health and your relationship at the same time.