In the beginning of the novel Katniss's sister, Prim, was chosen to compete as a tribute during the reaping. Katniss couldn't bear the thought of letting Prim participate so she volunteered and took her sister's place in The Hunger Games. This shows that Katniss is brave because she was willing to have her life end just so her sister could be safe.
After the tributes had boarded the train on their way to the Capitol to compete in the Hunger Games, Katniss had asked Haymitch for some advice and he had replied with "heres some advice, stay alive". this angered Katniss as she was frustrated that Haymitch was paying more attention to drinking than helping the tributes learn how to survive during the Hunger Games. Katniss decided to stand up for herself and get Haymitch's attention so she stabbed a knife in-between his fingers. This showed an act or braveness and courageousness as she stood up for what she believed was right despite the consequences.
During Katniss's private session, none of the game makers or sponsors were paying attention to Katniss because District 12 is the one district people don't pay as much attention to as they never are surprising or interesting in any way to them. When Katniss noticed that nobody was watching her performance she shot an apple straight into a pigs mouth. This shows that Katniss is a hero or shows acts of heroism because she wasn't only standing up for herself but for the inequality her and Peeta were facing. This has been a common trait that we have noticed in Katniss as she stands up and looks out for others before herself.
Please at least try to win Katniss
I will Prim, I promise
During this moment in the book, we have read that Katniss ventures off into the woods quite often to get away and to hunt to find food for her family. Although this act could be consequential to death sentence she continues to do so as she knowns that her family will not be able to survive without her looking out for them since her father had passed. This again shows an act of courageousness as she would do anything to protect her family even though that could result in severe consequences for herself.
When Peeta and Katniss were riding on the chariot presenting themselves to the world, Peeta wanted to hold Katniss's hand as the crowd would "love it" and their love story would become more real to the audience. Katniss did not want to hold Peeta's hand as she does not want to show affection for someone who is going to have to try and kill her. Even though Katniss had these doubts she still held Peeta's hand because then she could possibly earn sponsors. This showed an act of bravery as she went out of comfort zone because she knew if she could get sponsors she would have a chance at winning and would be able to go back home to Prim.
When Katniss was saying goodbye to Prim she showed bravery by staying strong. Even though she wanted to break down and cry she stayed strong knowing she had to do this for Prim.