One of the ways that I have success getting reluctant writers to put pen to paper is to have them freewrite a poem and then use that poem as a prompt for further writing. I do not place restrictions on what their poem can be about. I tell them to focus on a feeling (emotional and/or physical), a memorable experience, a vision, a song, or even to make something up. The poem does not have to have a particular structure, doesn't need to rhyme, it just needs to come from within them. Some of the best poetry I've read is a result of this exercise. I model for them by writing an impromtu stanza or two (usually a poem I've already written:). For example, I shared this poem that I wrote in the Summer of 2011:

Zen Moment

Floating on my back,
buoyant water my lifeline.
The only sound, that of my
beating heart, pounding in my ears.
I open my eyes to a perfect summer sky,
Blue, white clouds forming shapes
I could not discern.
Such beauty I have not seen,
in a long time.

A tear came to my eye
as I realized
how much beauty
has gone unseen by these eyes,
that have only been 1/2 open
for far too long.

Now I've connected with my students as I share a personal moment with them. The poem is written in everyday language, it doesn't rhyme, and I've randomly broken it into two stanza's so it looks more poem like.
After they have written their poems I tell them the story behind my poem and ask them to write a brief narrative of the motivation behind their poem. It's a great freewritng exercise because it allows students to write about something they know, without the rules and organization requirements of a more formal writing, and students, (referring here to 9th & 10th graders), seem to have fun with this type of exercise.

Hope this helps

Peggy