1. Base on CMS, WordPress, Drupal, Joomla, your choice.
2. Responsive, IPhone 4 is the smallest screen size
3. User Publish New Year resolutions, e.g., I will lose 30 pounds in 2015, I want a girlfriend in 2015, esc.
4. Tasks or Actions to be taken to keep the resolution,
1) Suggested Task, kinds like autocomplete, in case the resolution is lost weight, tasks may contains limit eating garbage food within 10 times, walk 500 meters per day, esc, Post pictures along the process.
2) A maintenance page to update the suggestions
3) Update Tasks status, show animated congratulation splash when some tasks have been finished, like the pages when you pass a game level.
5. Articles, this might be combined with blog, such as Top 10 Resolution in 2015, Top 10 Resolutions that has become true in past year, top 10 Funiest Resolution,esc.
6. Blogs, such as how to achieve your goal, esc.
8. SEO, Attracting traffic, Google AdSense.
9. Paid Membership, resource for paid members only, Base on CMS, Drupal, Joomla or WordPress, your choice
10. Online store, PayPal
Actually, I do not have any more details, so, you have to do some research and thinking.
I would like to share the income from this website if you share my vision.