Even people with excellent qualifications and impressive work experience sometimes struggle to articulate what they are looking for in their next job.  Can you express it in your language?  It's not easy.

‘I am looking for a challenge’ – this is the most typical and widely acceptable thing to say. But you need to be able to explain more about the kind of challenge you are looking for.  ‘To continue developing my skills base, I now need to concentrate on my people management experience and so I am looking for a position that will give me the opportunity to line manage.’  Imagine you have been doing the same job for more than five years – you might be bored.  But you don't want to admit to that in an interview – so you could say something like: ‘While I continue to enjoy the position I am now in, I feel the time has come to push myself in another direction.  I want to consolidate on the experience I have gained and try to develop my interpersonal skills.’

Alternatively, you may have been in your job less than a year and you hate everything about it.  You need to give the impression that you are reliable, because employers will be reluctant to hire you if they don't think you are.

So you can say something along these lines: ‘I knew after only a few months that I was not going to be stretched enough in the ways I wanted to be.  I feel that it is important to commit to a job and an employer but I also know that my performance can suffer when I am not being challenged, so I took the difficult decision to actively look for a more demanding position.’