Answer: Many things depending on who you are! Maybe its ice cream, or bungee jumping, or quiet walks on the beach, or doing crossword puzzles in the bathroom. But if you were Albert Bond Lambert, the answer to that question would be airplanes! Albert loved adventure from his youth on. He first satisfied his thirst for adventure with motorcycling. That gave way to ballooning. Once the Wright Bros proved the viability of the fixed wing aircraft, Albert was immediately intrigued. He took lessons and bought himself a Wright brothers built aircraft. Not only did this become a hobby of his, but as a business man he could see how airplanes were going to change the world. Thus (yes...i said thus) he became a major investor in aviation and aviation infrastructure. I hear he also still really enjoyed doing crossword puzzles in the bathroom though. Some old hobby's are hard to let go.
The illustration below is for the Notable Missourian book on Albert Bond Lambert. This book was written by Christopher Lynch and published by Truman State University Press.