What keeps you from crossing the threshold from not writing to writing

A doorway, no door.
On the other side, light
and green, even flowers.

If I step through
what do I leave behind?
Where do I go
if I step through?
What if it is so pleasant
on the other side
I can't walk back through?

Why would I go back
to Not Writing?
Because I know it.
Dark, its corners,
small warmth.
A roof, walls, no windows.
The warm comfort
of a small space.
Shelter.

The threshold calls:
the sun, the green,
the other side invites.

I hold my breath.
My own fear keeps me here.
I look around
the edge of the threshold.
Sun bathes my calf.
My arm now into the light.
Inertia is heavy.
The light moves up
to my shoulder.

A dappled gray mare
grazes. Turning to look at me,
green grass hangs from her lips.
She shakes her head at me.

I move toward her to ride.