The question is, as a local politician who has never held a state office, would I have a chance at all at convincing the voters of the commonwealth that I would be their best choice for senator? Running for an office such as senator requires an organization and funding, and at the moment I have neither one of those. I can collect 50 Brookline signatures myself next year to run for re-election as a Library Trustee. Collecting 10,000 Massachusetts signatures would require many, many volunteers (or paid workers) throughout the commonwealth.
Also, I'd need to make my platform explicit; a website would probably be a good start.