From wikipedia:

The basic message of Tolle's book is that our mode of consciousness can be transformed. The key to becoming free of the egoic mind, with all its consequences, is to become deeply conscious of this present moment, or, as Tolle often calls it, "the Now."

From the Now book:

"In your everyday life, you can practice this by taking any routine activity that normally is only a means to an end and giving it your fullest attention, so that it becomes an end in itself. For example, every time you walk up and down the stairs in your house or place of work, pay close attention to every step, every movement, even your breathing. Be totally present. Or when you wash your hands, pay attention to all the sense perceptions associated with the activity the sound and feel of the water, the movement of your hands, the scent of the soap, and so on. Or when you get into your car, after you close the door, pause for a few seconds and observe the flow of your breath. Become aware of a silent but powerful sense of presence. There is one certain criterion by which you can measure your success in this practice: the degree of peace that you feel within."

This is bad self-treatment. This is exactly How I interpreted his book -> Forcing oneself to stay in the now, the get rid of this "ego".

The correct approach is:

"I don't care about the Now,
if my mind is not in the Now,
this is because I have problems
like everybody. I have solve these problems first.
I solve them slowly, without forcing myself. "

Magically, it works. We find peace with the Now. If it doesn't work, no problem. It may work later. The goal is not reaching the Now, the goal is finding peace with self. Now is the natural, secondary, result.

The fact that it is a best seller doesn't mean that the Tolle's book is correct. It only shows that the topic is interesting.