Lithril
I've had a similar experience, years as a birdwatcher meant that I could walk through a forest, much of the time looking upwards, and identify a multitude of birds by sight, sound, behaviour. Then one day I realised I couldn't tell what kind of trees I was looking through and it kind of spiralled out of control from there. Started looking at the wild flowers etc etc. Went on a Woodlander course with Woodsmoke and when I got back discovered that a walk which took me an hour before was up to three hours easy because there was so much to pay attention to.
I'm sure that realisation that there is stuff to attend to is key, a course can help but learning what's what and how to see things is a personal thing, and bloody great fun too.
and then you start noting the animal sign......