Living in the present is not something everybody does, and those who don't miss out on their own lives. Some of the negative thoughts that we pay attention to are related to worrying about the future or resenting the past. Whenever you do any of these activities, you are not living in the present.
Neither the future nor the past
It does not make sense to worry about the future, as we don't ever live in the future. We live only in the present. Most of the things we fear don't happen, anyway. Besides, the main practical problem with fearing the future is that you think about the future situation from the thoughts, emotions and beliefs that you have NOW, which will be different when the future situation comes about. So any future you imagine is, in this way, a lie.
It does not make sense to resent the past either. The thing is, you cannot change the past. Why would you like to re-live and suffer something you cannot do anything about?
A distracted mind is a field where concerns and worries grow easily. Living in the present is key to nurture a life free from worries.
A Present Poem
Let me leave you with this poem attributed to Buddha that reflects the philosophy of living in the present:
Don't chase after the past,
Don't seek the future;
The past is gone,
The future hasn't come.
But see clearly on the spot
The object which is now,
While finding and living in
A still, unmoving state of mind.











