Every time you repeat to yourself something it becomes imprinted. Eventually the imprint goes deeper and leaves a stronger impression.
Here are some that I picked up that I now use every day.
Today I choose to be happy
I am grateful for everything that I have
I choose to focus on those things I can control
I am capable of achieving great things and do so daily
I embrace all of life’s challenges as an opportunity to grow
I am committed to continuous improvement
I choose to have a positive impact on the world today
I am always at the right place at the right time with plenty of time to spare
Every day in every way I am better and better
Try repeating these often for 30 days and notice the shift