I mainly practice walking meditation in nature which you've already mentioned. Another possibility would be
which I love because it's way easier due to fewer distractions coming from the environment. What's so fascinating about it is that you only move as the spirit moves you, which means that you don't have to follow a set choreography as in taiji or perform specific exercises as in qi gong but only move spontaneously (and that may include not moving at all for some time!); neither is it about expressing oneself or violently venting one's feelings. The way it's practiced in the Subud system is that you surrender totally to god but the way I prefer to do it is to let go of all my conscious volition and let my body move of its own accord. It's mostly subtle movements, like shifting my weight, allowing my arm to rise slowly, then standing still for a while, whatever comes up. I never analyse what I'm doing, I just let it happen while my thoughts drain away.
Hands-down the best method of achieving trance for me is the slow basic step (
ginga) of capoeira angola and some variations thereof. Forget all you think you know about that Brazilian martial art, capoeira angola is slow-mo and hypnotic, and its music even increases the trance effect (I've written about it
in my forum journal). It's gentle swaying, sometimes pausing and breaking the rhythm, taking a small step into a different direction, stopping for a moment, leaning back a bit and performing some sluggish hand movements, then continuing… in some way it's like Latihan, I never know what I'm going to do next.