How important it is to be happy with your work/career?

While working as a nurse...and you feel you are not happy anymore with what you are doing....thinking of a second career...???...reading a lot of comments/posts/advise not to change career because salary wise,you have a higher pay being a nurse compare to the second career that u are planning to take(ex:Pharmacy tech leading to Pharmacy)...and it took you a long years/effort before u became a nurse....but how about urself???are you always going to think of what other will say...what if you are not happy anymore of what u are doing???
While working as a nurse...and you feel you are not happy anymore with what you are doing....thinking of a second career...???...reading a lot of comments/posts/advise not to change career because salary wise,you have a higher pay being a nurse compare to the second career that u are planning to take(ex:Pharmacy tech leading to Pharmacy)...and it took you a long years/effort before u became a nurse....but how about urself???are you always going to think of what other will say...what if you are not happy anymore of what u are doing???