Following the theme of literature, it's obviously a pretty high goal to 'write a first novel', and clearly even more challenging to have it published, then for it to be a success.
Most of the normal life goals that can be gamified should be more achievable but should be scored on how 'advanced' the achievement is.
Suppose you just want to become more widely read, and challenge both the genres and quality that you normally choose. There are a few ways of doing this but imagine firstly that a generally agreed list of the 'best' novels ever written. These could be ranked by how much of a given population actually reads them, and assign a challenging score based on this ranking - maybe with an exponential curve component that increases the score based on obscurity or difficulty.
This would give incentive to really stretch in order to gain a decent return on investment (as far as score goes). It's fairly easy to also imagine asking for a list of common genres or authors, then providing a higher score based on reading outside of these areas.
From here it leads into forms of evidence. Perhaps you get the base score for claiming to read a novel, a multiplier is applied for further evidence - a photo of you reading the book, a simple enjoyment rating, a book club presentation, a full review or summary.
Something like this perhaps:
For the completists among the community bonus score could be given for reading all of an authors work, or all in a listed genre.
Now, imagine this is continued into other forms of accomplishment: places to visit, bands, sports, types of food, theatre, movies, skills, languages, activities, martial arts, volunteering, etc.