I already have a good exercise habit, going to the gym 3 or 4 days a week. Does the habit have to be daily?

Eva N.
Absolutely not. If that routine works best for YOU then stick to it. It never has to be everyday unless you are told by a doctor. But if your routine works stick to it, and if you want to change it go ahead.
Darlene T.
No. You have to give at least 1 day a week to rest, and if you like going to the gym 3-4 times a week, don’t force yourself to do more. If you still want to exercise, you can do yoga, or go for a short run