I Have A Lot Of Brown Spots On My Skin.

I have a lot of brown spots on my skin. It gets darker and more dark spots shows when the weather gets warm. It has been about 10 years. I do not go under the sun. I work indoor and long hours. what kind of treatment is good for me to have a good result and does not need to have time off from work?
I am 58 years old and a healthy Asian woman.
Misook