How can I be happy if I have losses?
It is vital that one attain the wisdom to recognize that losses are not determinant of happiness or unhappiness, but are just parts of life, parts that are not tragic in 99.9+% of the cases.
When we make up stories about what could happen or how bad off we are, then we match all of our internal recordings related to that and we experience the negative emotions, though, in 99.9% of the cases it was not something we needed or will need for happiness. We just live an illusion and we believe it, seeing the motion picture over and over and feeling the requisite (mostly negative) emotion. Pretty silly!
The opposite of losses is "haves".
To offset the idea of losses, it is useful always to spend more time in seeing what one has - and the effect will be that you'll be much happier.
In fact, Gratitude, and implicitly appreciation of something, is one of the very key skills and practices that will contribute to your happiness.
BUT HOW CAN I BE HAPPY IF I HAVE LOSSES?
But, you ask, how can I be happy if I have losses?
A good question. (And I have a good answer for that!)
Interestingly enough, it is inevitable that we will have a certain amount of losses and that that is just part of life. So, a good life = gains - losses. If we are unrealistic and resist this, we come up with the idea that we shouldn't have losses (kind of like a spoiled child who wants it all his/her way).