In my humble opinion, concentration is a skill (and not a method) that can be cultivated in any environment. Dharana is a state that one reaches when concentration is successfully used in the inner domain.
And ability to use the worldly skills in the inner domain becomes possible/ successful only after the break through achievement of pratyahara, non-attachment. Breath-watching teaches us to be aware of something subtle that functions in the gross body. But that has to go hand in hand with thought-watching. Since our awareness arises from thoughts, any awareness of thoughts automatically slows them down.
Kowtaia and Nath ji, it is not contradictory to watch the thoughts and not be aware of the thinking process. In fact, the latter is a natural progression of the former. By deciphering the process one understands its components like triggers, emotional baggage, regrets for the past and anxiety for the future, so that they could individually dealt with. Are we not talking about anxiety in this thread?
After pratyahara the practice of breath and thought-watching remains characteristically the same, but improve in finnese. Pratyahara lets you in, state of dharana marks efforts to stay in by bringing back outward orientation, state of dhyana is reached when dharana is sustained by elimination of efforts but one remains aware of it and finally, samadhi state makes us loose even the awareness.