Every experience you have in life should enrich you in some way. Even the bad experiences will leave you something- a feeling, an effect on you or maybe a new turn in life. Because of an experience, your life could change, your goals could be reset and your direction re-calculated.
Musicians have always used the everyday experiences both good and bad to draw from for material for their music. Poets and writers tend to do the same, if not, why not?
When an experience is so significant as to make you feel something intensely it is grist for your mill. This type of event leaves its mark which in turn can have you re-examining your whole life. It might make you see that your priorities are wrong. It could result in the knowledge that you have been wasting your life due to past events and this acceptance of that fact could help you move forward.
Experiences such as death of a friend or loved one produce grief and often a re-evaluation of your own mortal life. The grief you may experience can be all encompassing and enrich you even though the feeling is not pleasant.
On the other hand, the joy of a new baby or special holiday celebration will enrich you in quite another way. It will increase your feeling of valuing what you have and all the blessings currently being bestowed upon you. The significance of how lucky you are could produce feeling of euphoria that will enrich your mood and thought process. It seems to me that the happy times result in an appreciation which extends itself to your writing.
Of course, there are many other experiences that do not fall into the sad or happy category, but result in other emotions. An experience such as being angry might help you examine your too quick temper or help you explore ways to slow down the explosion when the fuse is too short.
A learning experience can be very enriching for obvious reasons, but many more subtle changes may result. Besides gaining knowledge, it could help with skills dealing with people and be a lesson in human nature as you work in groups to achieve a goal or create a project.
Worry is another less than pleasant experience which teaches and enriches as you see the complexity of life and try to find ways to solve problems or meet challenges.
Each and every experience creates something that can be used to enrich and teach you more about life. These can be valuable experiences for a writer. When they take the time to really understand what is happening to them, they are the better for it.
Shhh! Can't you see I'm writing? 