Inhale through your nose for 4 seconds; hold for 7 seconds; exhale through your mouth for 8 seconds; repeat.
This really works, but I always had a hard time remembering the numbers and their order, so I came up with this saying: “Who do you appreciate? Inhale 4, 7, 8!”
“Inhale 4” means inhale for four seconds. Since the only logical next steps are “hold” and “exhale,” it follows that they are seven seconds and eight seconds, respectively.
One Idea 