haha.. thats cool. do you the online already?
What you're looking for is validation, and you're not going to get the results you need from CFL Discuss. This is going to require firsthand research. And instead of asking, "Here's what I'm building, do you like it?" you will need to find out who people are that care about mindfulness, what they do now to remain mindful, what else they may be willing to do to be mindful, how they feel about technology in general, how they respond to reminders and other forms of encouragement, what rituals they follow already, what interruptions they dislike, and other things about their habits like what they find easy to remember or forget, and what makes them feel like they've accomplished their goals. This should inform you whether your specific idea has any hope of fitting into their world. You should also separately look at groups of people who use electronic reminders for other purposes and find out how they interact, what they like and dislike or would change about the reminders they're using now, and probably some other things.
If you just ask, "Do you like it?" or "Would you use it?" the answers are not reliable enough to guide you in a decision to move forward with development.
My assumptions, and each one would require individual testing to find out if they hold true for a large number of people, include these and more:
1) people who are very interested in mindfulness set aside technology, and for example, turn off their smartphones when they are at home
2) demanding a specific resolution to a reminder creates anxiety, not mindfulness
3) a reward for completing the action rather than a penalty for not completing the action would be more motivating
4) any competitive or gamification aspect of the action is going to make it less mindful
5) there is going to be a steep curve to making this a habit before stopping it feeling annoying
These are just some initial assumptions to test. My gut reaction is that this is a terrible product idea, but I'd be happy to be proven wrong.