Is this a stupid idea? They both interest me. Where could I go with this in terms of job opportunities?
If you’re interested in both but concerned about job opportunities, get the CS degree and read books on Kinesiology. A double major won’t have much overlap, so it will take an extra load of classes or another year or college. A double major also most likely will not enhance your job qualification, just widen your field. In this case you could get a computer-science related job OR the kinesiology related job, but it won’t make you much of a better candidate for a CS job or much of a better candidate for a Kinesiology job, just widen your field.
Do a double major because you love the two majors.
Don’t double major to look “good”
In a financial point of view, it is not recommended. You really don’t have any benefits double/triple/minoring in a subject. And if you think the two degree will help you get you into some fascinating kinesiology research that encompasses algorithms…it doesn’t, trust me.
That said, double majors are a great choice if you truly want to learn both standardized curriculum. I mean, you got like 128 credits all 4 years. Might as well split half to one of your passion and half to other rather than waste the other half on random classes 
And oh ya…you don’t have to major something to take that class. Many math majors I know of took like 6-7 CS classes because they enjoyed CS. They never bothered with a CS minor or a CS degree but hey…they were extremely good at CS so ^^
I definitely agree with the “do a double major because you love the two majors.” Don’t worry about trying to figure out how to combine them into a career right now; you can always concentrate on one or the other in the future, and I think that having the option to concentrate on one or the other, or parts of both, will be nice.
I would also say that for now it can’t hurt to take classes in both areas. If you decide that you don’t enjoy the classes in either compsci or kinesiology, you can drop it or just do a minor in it. I wouldn’t write anything off until you’ve done some of both.
Complete agree here with above poster. Do what makes your feel happy and what you like even the 2 majors aren’t really related. I made the fatal mistake of majoring in something that didn’t really interest me even though they were both related.