Now that you have that left over fabric from making the work out racer tank, why don't you make a matching hairband to keep sweaty hair out of your face.
Cut the seam of the end of the sleeve. Then cut about 9 strips at about half an inch to an inch wide.
Pull on the strips to make them curl up.
Take one of the strips and wrap it around the other strips and tuck the ends into the knot.
This is what it will look like when you are done.