We can choose to be happy. This may seem hard or even impossible at times but we have the choice. It takes a lot of self-control and acceptance of present circumstances perhaps but it is not impossible. Since what we currently perceive is based on past experiences, it is often healthy to cuts links with the past (which doesn’t exist anyway except in the form of memories). I believe there is truth in the saying “Ignorance is bliss” – as long as we don’t take this to extremes. I also find for myself that I can be happy with very little. In fact, a surplus of possessions actually stresses me – so be happy with what you have and don’t wish for more ! I also don’t allow my happiness to be influenced by the whims and expectations other people. The less you expect, the lower the possibility that you will be disappointed ! Don’t worry too much about the future either. This can result in paranoia ! Be happy by focusing on the present moment. If you have a problem that is difficult to solve, then changing your opinion about the problem can make it go away !
I recommended reading the excellent books by HH the Dalai Lama and by Eckhart Tolle.