Why do my poems always seem to end up in iambic pentameter?

Revealed--a dusty shard of memory
Forgotten fragments of a long-lost dream
Come forth with sudden perspicacity
And standing out like Islands in the Stream

Caught and glimmering, shining in the light
For one brief moment bursting into song
The fleeting glimpse of hope I once held tight
But when I reached to grasp it, it was gone

And in my small still empty outstretched hand
Are only aspirations, yearnings, goals
That slip between like silky grains of sand
Yet sear my hands and soul like burning coals.