When you choose to say "No" instead of usual Yes, when you choose to say something instead of keeping silence. When you choose to respect yourself instead of letting someone walk all over you. When you choose to take action instead of just observing.
Be aware of those tiny moments.
So, what can you do to change what could happen?
First, you need to know you don't have to let your circumstances or emotions take over you.
You can't control what's going to happen, but you can choose how you respond to them.
At the moment when you choose how you respond to what happens in life, that's the moment of truth when you change your life.