All shoes begin to wear thin on the soles sooner or later, and if they are favorites, you may want to repair or replace the soles rather than just throwing them away. If your shoe already has replacement soles and those have gotten worn down and loose as well, you can perform a simple repair yourself instead of taking them to the shop to have the soles replaced again. For this, use a shoe-specific glue, such as Shoe Goo.
Clean the shoe and sole thoroughly before applying the glue.
Apply the glue to the sole and expose to the air for several minutes before pressing it to the shoe.
Press the sole firmly to the shoe. Get the positioning right, as when the glue dries it will be permanent. Since Shoe Goo can take 25 hours to dry, the shoe and sole will need to remain pressed together for a full day. If needed, secure the shoe with a clamp.
Once the glue is dry, inspect the outside for any excess glue that has steeped out. If there is any, put some paint thinner on a rag, and rub the rag against the excess glue until it is rubbed off.
If there is a hole going all the way through the sole, put some tape over the inside of the sole before applying the glue.
Do not let the glue touch your skin.