perhaps you could try making really tiny projects. like, ridiculously comically small. a song that is 1 second long, a webcomic consisting of a single 8x8 pixels panel, a programming language with two instructions total,... whatever. if the project is tiny enough, then by the time the anti-motivational thoughts are able to kick in and say "aha you are Doing things, i don't want you to be Doing things", you've actually already finished the entire project.
the problem with this is finding something small enough that's still somewhat interesting to make, i guess. idk