1. Smile and laugh
The physical act of smiling activates pathways in your brain that influence your emotional state—meaning that by adopting a happy facial expression, you can "trick" your mind into entering a state of happiness. This affect works whether or not your smile is genuine..
So basically, if you smile, you will be happy.
2. Imagine you have solved all world problems
There is no need to be humble in your imagination. You can imagine every day how you achieved great things and how everyone is praising you and making statues of you everywhere.
3. Imagine you are better than anyone else
There is no need to be shy. Just imagine that all other people are morally and intellectually inferior. Imagine that you can do things no one else can, such as lift a building or memorize a book in a second.