Here is a very simplified summary of specific ideas derived from the Works of Friedrich Nietzsche (1844-1900) that are widely accepted without the slightest awareness of their origin and even by those who profess to loathe the author and the philosophy which introduced them. I wish to thank Paul Brians for his scholarly work and recommend a visit to his page the URL for which appears at the end of this post.
 The goal of life should be to find yourself. True maturity means
discovering or creating your own identity.
 The highest virtue is to be true to yourself.
 When you fall ill, your body is trying to tell you something;
listen to the wisdom of your body.
 People who hate their bodies or are in tension with them need
to learn how to accept and integrate their physical selves with their minds instead of seeing them as in tension with each other. The mind and body make up a single whole.
 Athletes, musicians, etc. especially need to become so attuned
to their bodies that their skills proceed spontaneously from the knowledge stored in their muscles and are not frustrated by an excess of conscious rational thought. (C.f. of Zen Buddhism)
 Sexuality is not the opposite of virtue, but a natural gift that needs
to be developed and integrated into a healthy, rounded life.
 Many people suffer from impaired self-esteem; they need to work
on being proud of themselves.
 Knowledge and strength are greater virtues than humility and
 Overcoming feelings of guilt is an important step to mental health.
 You can't love someone else if you don't love yourself.
 Life is short; experience it as intensely as you can or it is wasted.
 People's values are shaped by the cultures they live in; as society
changes we need changed values.
 Challenge yourself; don't live passively.
To learn more about the enormous influence of Nietzsche on our Culture: