How could we be living in anything other than the Now?
Everything takes place in the Now, so we are always in it, but our mind is usually somewhere else.
Being consciously fully present in the Now required that we bring our attention out of the mind - and this is impossible to sustain for long. The mind wanders, feelings arise - and off we go again.
So don't be annoyed with yourself, it is an incredibly rare thing to be able to stay fully present for more than a few moments at a time.
Practice does help and there is an inner motivation to do it because being present, in a state of no thought, has its rewards. The stillness of the Now and the increased peace that results from being present, keeps us wanting more.
But don't take my word for it, just keep coming back to the Now when you remember, and gradually it will becomes increasingly easy and rewarding.