i'd either concentrate solely on your breathing (in.....out.....in......out....) or not at all.


a number of times i have been drifting off to sleep, and vaguely feel "i'm not breathing', right before i take a deep breath and break my concentration. i've learnt to ignore any such fears, and let my breathing regulate itself...

although, as others have mentioned, the method you appear to be using is typically quite difficult for beginners (and many experts). i'd recommend researching DILD's, WBTB's, HILD's, etc.

good luck