"I prepare myself for the weekend."
Translation:Jag förbereder mig för helgen.
I wondered the same thing myself. I think it is answered by Arnauti in this thread https://forum.duolingo.com/comment/6717047
Förbereder is a reflexive verb, so själv is not needed, it is implied with 'mig'. In the part of the tree where I encountered this, Verbs Present 3, there is another verb learned, överraskar (surprise), which is not reflexive, so själv is needed when you say 'I surprise myself' - 'Jag överraskar mig själv.
Would be nice if a native speaker could confirm this.