Iin I want to change my name at 40?

Could be worse: you might have been named after your father's favourite stripper. Candy, Amber, Tiffany, Krystal, Brandy, Jade, Cherry, etc.

As you must know, people don't often change their name at your stage of life. So unless you're also planning to uproot yourself, move to somewhere completely new, start a new job and build a completely new life, I can see this causing all sorts of problems of varying degrees of seriousness. Friends finding it difficult to make a sudden change to a new name, the impact of a name change on official records and documents, the name on references from previous employers needing to be explained to prospective employers are things that immediately come to mind.

Frankly, I have to wonder if you're fixated on this idea because you believe that simply changing your name will have a magical, transformative effect on your life. Things are rarely that simple.