Living in the now is a great concept, but as a living reality, it is impossible to sustain for more than a few moments at a time.
Of course everything does take place in the Now, so you ARE in the Now - but being in the Now consciously takes continuous attention. And that is impossible.
The only way that being permanently in the Now is possible, is if you have transcended thought to a degree where your natural state is in the Now and thoughts are only present when attention is placed on them.
How many out there have that experience!?
We get swallowed up by our thinking and day-to-day lives and forget to stay 'present', but dont worry about it. Although it is very powerful to be present, relax about staying in the Now - it is totally impossible for long - just keep coming back to it when you remember.