Enjoy life and all the things you have at the moment because you can't have everything all at once.
Referring to: 9GAG - Lesson in life...
3 stages of life.
1. TEENS: You have all the time and energy but no money.
2. WORKERS: You have the money and energy but no time.
3. OLDIES: You have all the time and money but no more energy.
So true!
It's easy to say but hard to remember this.
So I simplify it to: Appreciate what you have right now.