In trying to make characters more lifelike we often push hard to examine and explain to the reader the character’s feelings. However, if it were that easy we wouldn’t need psychiatrists and therapists would we? Sometimes we feel inner turmoil, a struggle with something that we can’t understand. Sometimes there is just a coiling feeling of ‘something’ that gnashes and claws at our guts, pushing us to act, to do anything to try to relieve that feeling.
Angst is an undirected anxiety. It is a word we use in most cases to describe that unsettled thrashing feeling teenagers get. But it isn’t solely the realm of teenagers. Everyone at some time finds themselves with a ticking time bomb in their guts.
The way a person deals with that feeling is determined by their character. We can talk partly about natural tendencies and about learned responses. The instinct is often a part of the “fight or flight” response. This is when a person lashes out. They get angry easily because they are on edge. Alternatively they will hide. Clam up, move apart from others and be all teenager with more feelings than they know what to do with. The other side is the learned response. Some people have learned to talk about their feelings, others have learned to turn inward and seek out the root cause of their unrest. In any case you might describe it as a kind of quest for peace.
When writing a character it is helpful to remember that not all feelings are so easily described or attributed. How about a character who is all angsty and so snaps from time to time. They go all angry and shout and carry on. Or you could have them retreat. In either case you don’t need to explain to the reader exactly why the character has done this. it is sufficient to say they feel a ball of heat in their belly, a fire so hot it feels like it could hollow their chest out and leave nothing but smoking ruins.
Try going without sleep for a couple of weeks while looking after a baby and you will begin to get a handle on the concept. Trust me.