Breath in and out in growing counts of heartbeats per inhale and exhale and make sure you allow at least one or two heart beats for the pause during each phase. When you reach a point were you become slightly full, relax during the pause stage and make sure you become aware of the gap between the extra tension you are using and the form and tension after you relax during and after the inhale or exhale. As you become more comfortable and relaxed add another heartbeat or two to the Inhale/Exhale phases and again relax with awareness during the pause so you notice and automatically correct your effort and nerve/muscle engagement. Again move forward and backwards with this as you focus on the breathing being done with the least effort and utmost relaxation by becoming aware of the extra work you do due to the intention getting in the way.
I like to do this while driving or walking as it adds to my relaxation and capacity to notice things going my way ahead of time and it can be done almost anywhere and unnoticed.
Different times and locations will bring out different focus and sensations. Be aware of it and it’s effect will not control you.