Well-being can be broken into five elements:
If you improve these, you will be closer to happiness.
Pessimism comes naturally to people because thinking about the bad stuff that could happen helps us to prepare for survival.
The problem is that pessimists think bad events are permanent and unchangeable. "I think my interview is going to be a disaster." We need to learn to recognize what we're saying to ourselves and then argue against it. "I've done many interviews in my life, and they generally turn out well."
Meditation - mindfulness, focusing on the moment - is an excellent anti-anxiety, anti-anger tool..But accepting suffering and finding contentment in that means you can't move into doing something good in the future.
One important idea is hope. Positive human future doesn't come about by accident - it needs hopeful people who plan for it and make it happen.