How do you make a statement about the past without saying anything about the present?
Solution 1:
For most verbs, the simple past tense doesn't say anything about the present.
For example, consider:
I went skiing last winter.
It doesn't imply anything about whether or not you've given up skiing.
For the verb want, the simple past can sometimes (weakly) imply that the situation is no longer true. For example,
I wanted to be a fireman when I was five,
generally gives the impression that you no longer want to be a fireman. This is because, if you still want to be a fireman, you would instead say
I have wanted to be a fireman ever since I was five.
(Of course, you could also use I wanted to be a fireman when I was five if you are currently a fireman, but probably not if you still want to become a fireman.}
So use a different verb than want.
When I was five, I decided I wanted to be a fireman.
When I was five, I knew I wanted to be a fireman.