Elastic straps are handy for keeping your shoes in place, but when they are too big, they can cause discomfort and irritation. However, as long as the elastic is still in good condition, it can be shortened to make your shoes fit better. Since shoe types vary considerably, the steps will depend on the design of the shoe. Use basic tools to do your own repair and save money.
Detach the elastic from the shoe using a seam ripper. Work from the inside of the shoe if possible, so that your work is not noticeable upon completion.
Pull the elastic tighter so that it will fit your feet, and reattach it to the shoe with sewing pins. Tuck the end under so that the raw edge does not show from the outside of the shoe.
Thread your needle with heavy-duty thread that matches the color of the elastic or shoe. Stitch through one edge of the elastic and shoe. Continue making small stitches across the elastic and shoe until the pieces are entirely sewn together. A zigzag stitch will help keep the elastic from coming off.
Knot the ends of the thread multiple times to keep it from coming undone. Cut off any hanging pieces of thread with your scissors.