I can't sit still.
Heck, I spoke to a friend who was trapped indoors due to bad weather a few days ago, and she said she was climbing the walls a bit (all she ever does is 1-2 hours gentle walking for exercise).
These would be signs that you had a problem:
Being too skinny.
Repeatedly Exercising when you had an injury the exercise makes worse.
Obsessing over calories in and exercise out.
Not being willing to juggle your exercise routine around other commitments.
Talking about your exercise routine constantly.
Repeatedly Criticising people who don't exercise like you. Insisting that your exercise way of life was right & others should convert or change themselves.
Thinking about exercise obsessively & punishing or depriving yourself in some way if you missed a session.
Paying crazy money to exercise, or even getting into debt, or repeatedly spending lots money on things you don't need related to the exercise.
Declining other social occasions consistently just because they interferred with your exercise plans.
Insisting on only socialising with people who share your exercise attitude.
For "exercise" in above list, one can substitute religion, clean-eating, veganism or politics, btw.