The other day, one of my roommates and I had an interesting conversation. We attend the same church, and we were discussing some of the adversity that people in our congregation are going through. Those challenges run the gamut of human experience: career decisions, mental illness, difficult school semesters, divorce, a parent with cancer, the long-term effects of childhood abuse, and probably more that we don't know about. A lot of it isn't pretty, and all of it is hard.
As we talked and commiserated for our friends, my roommate said something along these lines: "I may not have been through the exact same experiences as these people, but I've been through other hard things, and the feelings are pretty much the same."
That struck me as an important truth about both life and writing.
In our lives, we've probably all had times when we wanted to comfort or rejoice with someone but didn't know how because we hadn't shared the experiences that triggered those feelings. However, I think we all understand disappointment, excitement, anger, and so on, on some level, because emotions are universal. So, while we can't know exactly what's going on in someone else's mind and heart, we can empathize with the feelings they share with us.
So how does this apply to writing? Well, how many times have you heard the classic advice "Write what you know"? To a certain extent, this is a good tip. There are some things you can only learn from personal experience or from research. If someone calls Iowa "flat as a pancake," for example, I know that that person hasn't visited or seen pictures of my native eastern Iowa, where there are lots of hills. Or if a writer has a character get cracked on the noggin and then wake up three hours later with only a headache, I know that that writer hasn't done their research about head injuries. Either way, my suspension of disbelief and/or trust in the writer's credibility is damaged.
However, you don't have to personally experience everything you write about. (In fact, please don't!) Even if you've never broken a bone, battled an evil mastermind, broken up with someone, or whatever, you can still write about it convincingly. Do your research first, and then fill in the emotional gaps with what you've learned from your own experiences. If you've never broken up with someone, for example, think back to a time when you were severely disappointed (or relieved, as the case may be). If you've never battled a mastermind, recall how you felt during a confrontation with someone you didn't like. If you've never broken a bone, think about how you reacted when you got your finger slammed in a door.
Remember, emotions are universal. If you can get the audience to feel the right things, you've won half the battle.