The only thing that matters is right now. Right now you can take action or no action, there is no time but now.
There is much satisfaction living in the now moment. The power lies in your control over your emotional state. Concentrating on now removes you from your ego-self. You have no time to think about the past or the future and entangle yourself in those places that only exist in your mind.
My first real exposure to the power of now came to me at age 18. I started rock climbing, first in the gym then outdoors. Scaling a wall definitely helps you understand what you are capable of in a holistic sense. You get to know your strengths and your weaknesses real quick. Positive thinking is key. The slightest doubt in yourself can end in injury or death.
Now is all there really is. The past is done. The future is malleable. Both are out of reach. Do what you can now!
Just now I did this, and it was fun.
Have fun doing what you are doing, right now!