One day I will be happy.
Sadly, many of us keep convincing ourselves, "Someday I'll be happy." We tell ourselves 'I'll be happy when I will be a president, when I will be doing so and so service, get a particular mobile phone' etc. We convince ourselves that life will be better after we get married, then another, then another, on and on and on we go with our wish list.
Meanwhile, life keeps moving forward. The truth is, there's no better time to be happy than right now. If not now, when?
Your life will always be filled with challenges. It's best to admit this to yourself and decide to be happy anyway.
A wise man said, "For a long time it had seemed to me that life was about to begin - real life. But there was always some obstacle in the way, something to be got through first, some unfinished invention, a debt to be paid. Then life would begin. At last it dawned on me that these obstacles were my life."