Put on a jogging suit, prepare your vacuum cleaner, set your stopwatch, and then zoom through the house. One sure way to become re-energized with a topic is to teach others. Suppose you know how to bake a cake, or can juggle three balls. In preparing to teach someone else, you need to become excited about it yourself. Just the act of preparing will bring out new insights.
Many people say it's impossible to know the purpose of life.
There's a great danger here. Because when we say we can't know something, we give up the chase. Many people are afraid to ask existential life questions - often because of the great effort it takes to research and develop. Because even if you don't find the answer, the process of investigating will undoubtedly yield tremendous insights along the way. If you have the courage to keep that question at the forefront of your mind, you are guaranteed to never grow bored with life.