The Name as an Accessory
Saju is your DNA; it cannot be changed. Your name is the clothing you wear over that DNA. If you are born with a chart that creates an incredibly weak physical constitution (DNA), renaming yourself "Hercules" will not magically give you giant muscles.
However, if your chart lacks exactly one element—say, Water—using a name that carries heavy Water resonance can act as a daily psychological and phonetic supplement. Every time someone calls your name, they are handing you a cup of water.
Don't Rely on Magic
Changing your name without changing your habits is useless. A name change is a declaration of intent to the universe, but you still have to do the work.