Ok so you may not have any desire to be the next Kate Winslet but if you suffer from insecurities, shyness or a general lack of confidence acting classes may be just the thing for you! I know that for many who are shy or lack confidence acting classes may be a daunting prospect but they will be worth the investment I promise. Think of it like ripping off a plaster, you can either do it slowly (being shy or lacking confidence long term whereby it could inhibit your quality of life) or rip it off which may initially be sore however in the long run will hurt much less (i.e. acting classes).
Acting classes will encourage you to lose your inhibitions, talk to larger than life characters and also teach you how to act confident even when you might not feel confident.