Just looked at the requirements for 4th year Practical Placement at uni. It says, "Please provide a brief motivational statement. Include approximately 5 key reasons why you want to enrol in this unit, what you expect to get out of the unit and how this fits in with your long term career plans."
I don't even know what this unit entails, where the uni places students or whether the students have to find their own placement.
Plus I don't have long term career plans for psychology. I think about things like this and then I realise I am on a disability pension for a reason. It makes me sad to know that I would not be able to handle working in this field. It isn't for people like me.
I think you underestimate yourself, seriously. How many other people on that course have no clue what to put for those questions? I bet there is a few.
I think questions like that are designed to stump you, just so they can see how inventive you are with your answer! You could put that you think it will be a challenge, but that you are keen to push yourself. I don't know how relevant it is if it doesn't appear in your long term career plans - you won't actually KNOW until you do it!
Even if it does not become part of your career path, there is still much you could take from a course like that. You seem to be a very capable person, Ren.