Longer out than in
In for four, out for six. Nothing held, nothing forced. The simplest thing that works.
The pattern
Inhale 4sExhale 6s
Anywhere, any time, eyes open. The one to use when you cannot make a thing of it.
What is known
A longer exhale than inhale is the mechanism the exhale-focused practices share: the slowing happens on the way out.
Never practise any of these in or near water, or while driving.