The world changes. We become aware of such change by listening to how we feel. Whether in the wilds of the woods or life, if something doesn't feel right, it probably isn't. Look at it. Change your map accordingly. Make a course correction. It's the only way to get home.
Many things are beyond our control. But we are free to choose what we will pay attention to, the meaning we will give to our life. If the goal is to improve the quality of our lives, happiness may be the wrong metric. Pleasure or happiness is simply the side effect of living our best self.
I hope that with each of the days you have, you'll chase your goals, your dreams, your fire. That you'll act with that urgency of life in mind. Life is short. Don't count the days. Make the days count.