With any acting exercise character building will start. Not just the character you want to play, but also your own character. How? We will try to explain this.
Building a character means you have to discover a lot of aspects of the supposed live of your character. In your search you will also discover al lot about yourself. For instance, if your character bursts into tears, you have to know why, and understand it, feel it as if it was you. Thats a though journey. Because you are not the character, you'r the actor. But by relating something from your own life to the emotion needed in the play, you will make it a much more realistic performance. Mind you: this is important: it is not the situation that helps you to cry, but finding your own emotion.
An actor needs to be able to find all emotions. Every person has from birth all emotions included. But while growing up we learn to control them, and sometimes we control them so intense that we think we don't have them. One of my students once said: "I have no anger, I don't know how to play an angry character." Is that true? Can someone have no anger? Was Ghandi a person without anger? No, it is there, but he found a way not to use it to reach his goals. Anger is there! I asked my student to leave. She was surprised. I asked her again, and said that an actor needs anger, so if she lacked... "That is not what I mean", she replied. "I don't care", I said. "That is not fair, " etc. In the end she was angry. This is what triggered her to find her anger. She stayed and learned. An actor needs to find his own triggers that connect to the emotion.
There are many ways to do the search.
You can sit down with the script and write down all things already given. Now you know a lot of facts.
Lets see what the script might provide:
are you male of female?
What is your age, by calendar and your emotional, intellectual age?
During which era do you live, in which season is the play?
Does the script include what you want? For yourself, from the other(s), from live?
How are your feelings toward the other(s)? Can you express them or is it a secret?
Do you have a secret? A desire? Fears?
Do you have a job, or still in school, or unemployed? What is your education? How smart is your character.
With a complete list of questions like these, as being a top acting exercise character building will be easier and more logic. Always take the script as your base for the information you need.
While during your search by acting exercise character development is an interesting journey. Knowing this is the first part, understanding is much more. You have to find the reasons why you behave as you do.
The more you know about yourself, the more you can give to your character, to make it an actual living person. And isn't that what you want as an actor?