When the expression "things" is more appropriate than "what"...
ex.
"things you do" vs "what you do"

Are these interchangeable? If no, how are these used differently?
Example sentences would be appreciated. Thanks!Also, I'd like to know the difference in meaning and what makes these sentences sound natural or unnatural.

Question

When the expression "things" is more appropriate than "what"...
ex.
"things you do" vs "what you do"

Are these interchangeable? If no, how are these used differently? 
Example sentences would be appreciated. Thanks!Also, I'd like to know the difference in meaning and what makes these sentences sound natural or unnatural.

Answer

In some cases they can be used interchangeably.  However, there are times when one sounds more natural.  Some examples:

"I appreciate all the things you do for me"

"Do you like what you do for a living?"

ご自宅で快適に語学を学べるチャンスをお見逃しなく。経験豊富な語学講師陣の中からお選びいただき、今すぐ最初のレッスンにお申し込みください！