I just want to share an experience from my limited years of recitation.
Recently, I have started 'added' something into my recitation method and found that it has greatly improved my concentration and ability to stop unwanted thoughts creeping into my mind. The addition is recalling/ remembering an image of Amitabha Buddha. (I used the image painted by the late Venerable Dao Zheng.)
I realised that each time I recite 'Amitabha' while at the same time recalling Buddha image, I was able to stop other thoughts from showing up. I 'experimented' doing recitation with and without image recollection. The former method was always effective at getting rid of mundane thoughts. As a result, I was able to recite for a long period of time without feeling tired or disappointed
(sometimes I feel disappointed if I can't can concentrate as much as I like).
Is recollecting an image of a Buddha the same as visualisation? Will visualisation be even better? And how do you guys carry out visualisation?