1. Life is like a race, you keep on running. You try to get as fast as possible however, it is the special race, it's like a race against time, and not everyone can run long time, some have many years left, some may have minutes, but the point is, running as fast as you can before your time runs out. That's why life being compared to a race, because life is like a race.

2. Because, you can say an experience is a roller coaster, or roller coaster ride, if it's involves many emotional highs and lows, or really good times alternating with really difficult times.

3. It's because of the (smile), like full of surprises, and you never know what will happen next.

3>Hope it helps