We're not trying to breathe evenly or in any other way. What we're doing here is just watching the body breathe. Trust me, the body will breathe all on its own and when it needs to do so.
Although breathing is a natural reflex for most, some have to actually focus on breathing evenly. If we strive to allow our breaths to synchronize evenly, then we are able to relax and be more aware. To make breathing effortless would be to conquer fears and doubts.
Relaxing all control over the action of breathing is what I'm talking about. Use that mental effort you want to put into breathing into watching your body breathe.
This is not easy whatsoever. Your mind is going to want to intervene. Just relax when that happens and re-apply the mind towards simple awareness of the breathing.
Apply patience often, reduce control and effort. Breathe.