Even if you don't bring those into the conversation they'll play hell with the results--that may mean it's unavoidable to bring them into the conversation as "blockers" or "risks" and that potentially opens a can of worms.
One suggestion I'd throw out is to do the market research to figure out how many people have severe enough procrastination issues to benefit from your services, but who are otherwise sufficiently well-adjusted to not be more than you could handle. How many people out there really do just need another pair of eyes and a nudge, but are sufficiently isolated that they would have to turn to this kind of service to get them?
Otherwise you might find yourself in a non-existent niche between people who just needed a todo program and people who actually need serious help. If you don't screen out that second type somehow, assuming you're not set up to handle them, they'll potentially confound your scaling calculations by being exceedingly high maintenance and they'll have a bad experience as well.