Disclaimer: I owe much of the content in the middle and end to J.K.Rowling; the creator of the Harry Potter series.
The actual content:
Every time I open my mouth
I enter a whole new world
A world full of uncertainty
A world full of anxiety
A world full of fear
I hestitate to take a step forward
Lest I should be plunged
Down a steep, bottomless cliff
Lest I should be submerged
In an ocean deeper than the Pacific
Lest I should slip
And slowly sink in a quagmire
Full of rotting green slime
Every time I open my mouth
I am consumed
By an impending sense of doom
Hardly noticed by anyone
A cold steals over the surroundings
Followed by a rotting stench
Out of the gloom
Two hideous figures appear
Wearing long black cloaks
As they glide towards me
Hope swiftly drains out of me
Just like the water in the sink
When the plunger is pulled
My worst memories
Till now, dormant and buried
In a crevice
Deep inside the back of my head
Slowly creep up to the surface
And eat away at my spirit
Leaving me resigned
To the worst catastrophe possible
However, just as a candle flame
Burns the brightest before dying out
I dig into my deepest reserves
And summon one of my happiest memories
Before plunging my hand into my pocket
And whipping out my wand
To cast the Patronus charm
However, just as I open my mouth
I mumble and stammer
The Dementors pounce
Upon my fear and uncertainty
And place their filthy hands over my chest
A clammy cold, followed by a rotting stench
Overwhelms me completely
And I lose all my willpower
And wave a white flag
As I succumb to the Dementor’s Kiss
And my soul is sucked out
Through my mouth
Which I was rightly afraid to open