Simply replace the unfilled areas such as "" and "[date]" with your information.
I'm very interested in the [job title] position advertised [on/in] the [where you got the listing].
I'm currently employed full-time as a [title] at [name of company] and am doing [list any credentials you're earning, i.e. courses]. I'm looking for a new direction, for a job that gives me a sense of purpose and that I feel is important. I feel that being a [name of job] can provide me with what I'm looking for.
I'm interested in being [name of job] because it would help me apply and hone my existing skills and help me develop new ones. Through my work as a [previous job] and as [previous experience], I've developed strong [list skills] skills. I like to be kept busy, enjoy new challenges and work particularly well under pressure.
I'm a motivated self-starter who's looking for an exciting career opportunity. I'm willing to work shifts and travel as required, and I own a discrete vehicle.
I hope that you'll consider my application, and I look forward to hearing from you.