My son’s plans are to major in physics with a minor in environmental science (Geoscience) and math at Texas A&M. Math just requires one extra class, so that’s a given. But, the environmental science minor requires a few more. He will be coming in with a bunch of AP classes for the university requirements (english, history, etc.) but plans on retaking the physics and calculus classes in college. My question for physics majors, does that sound doable? I’m sure the physics classes get tough - is it too much to add a minor, such as environmental science? TIA 
This completely depends on the student. There is no harm in dropping a minor later, as long as he finishes a major and graduates. I see no harm in trying as long as he knows to seek help and/or drop a class if he gets in over his head.
It is absolutely possible. Many of my advisees at Illinois Tech have done this kind of thing.
@xraymancs Thank you! It is good to hear that a lot of students do this.
@trish02 if he’s just doing the math for resume padding and not because he wants to take another (or several more) math classes then he should just focus on the physics and the environmental science minor because most people (employers and grad school) are gonna assume he has a decent enough grasp of math based off of his physics major anyways.