If you're in your twenties or thirties you may be surprised to find yourself in this category. But what maturing skin means is that for some reason (like sun damage, smoking or stress) your skin is starting to act old. This means your skin may be starting to lose its natural glow or its elasticity. It's likely to be developing more lines and open pores. These things can begin as early as your mid-twenties. However, you can slow them down.