Apart from losing a bit of weight if you need to, the kegels are the best answer. They helped me tremendously. You have to concentrate hard and actually get in the habit of doing them practically all day at first. You soon can find yourself doing them without hardly thinking about it. Make sure to do them properly - think of the muscles at the back as well as the front. Draw them all in strongly.
You can get weights you put inside from Amazon and probably Boots etc. They may help, if you keep up with using them. But I think acquiring the habit of doing the kegels is most important.
It can be a hard slog but as yours is mild, you have every chance of turning it around.