What is that psychological illness called, when you don't feel like you are

doing the things you do? Sorry for the long question...but I can't remember the name of it!

It is basically when you feel like you are not totally there and not doing the things you're doing, or you feel not totally awake with yourself or something - I remember listening to a presentation on it and the speaker said to peel an orange and smell it, hug a tree and feel textures or something if you think you may have it.

I'm doing a project on illnesses like these and I think this one is really interesting to do, so if anyone can tell me it would be great.

Thank you veryy much!