I know there are a lot of bad things in this world, but don't waist your time focussing on them.
Try to look for the positive things in your life, your surroundings, your world and your negative feelings will vanish. Try to control your thoughts because they are the source of your (un)happiness.
Think about it. When do negative emotions come up? After thinking negative things!
So stop yourself and say "No. I will not go down this road again!' and start thinking about positive things.
You can change. You have the power!
Is it hard? Yes. Change always is.
But that doesn't mean it's not doable. Persevere and everything you want will be yours!