True power exists only in the present. There is no power in the past; the past is over and done with. There is no power in the future; the future exists only in your imagination. You have no power to act yesterday or tomorrow. Whenever you project beyond the present, you make yourself powerless because you're succumbing to an illusion. Consequently, it makessense to focus your attention on the current moment since it's the only place you have any real power.
We tend to think of time as a resource that we spend, similar to how we spend money. To complete a one-hour task is to spend an hour on it. How are you spending your day? Where do you want to spend your next vacation? How will you spend your lunch break? Although this is a common way to talk about time-bound events, and I often use such language myself, the framework is technically inaccurate. Time isn't a disposable resource. You can't spend time. No matter what you do or don't do, time passes on its own. You have no choice regarding wheteher to spend time or not; your only choice is how you direct your focus in the present moment.
In reality, you're never in the past of future. You exist only in the here-and-now. Even when you remember the past or envision the future, you're still thinking those thoughts in the present. All you have is right now, and that's all you'll ever have. You can't control the passage of time, but you can control your present focus. That's it - no past, no future, just right now.
("Personal Development for Smart People" by Steve Pavlina )