"Keep me motivated" or "keep myself motivated"?
Solution 1:
If the object of the verb is the same as the subject of the verb, you need to use a reflexive pronoun. So it needs to be:
I am doing this to keep myself motivated.
Similarly:
He cut himself while shaving.
The cat hurt itself when it fell from the tree.
You are only deceiving yourselves.
You use the personal pronoun as the object when the subject is someone different:
He is doing this to keep me motivated.