I would advise you to think hard about starting long projects for which the days of work that it requires do not individually seem worth the effort. Not only will you be miserable, but your chances of success will be low. However, I would also caution you not to assume that a long difficult task will not be satisfying day to day when approached with the right frame of mind.
You could not think of them as projects that must be finished, just work on whatever you feel like at the moment. Eventually they may grow to completion. If they don't, then you didn't like to work on them anyway.
(This is excellent advice from someone who has never managed to finish any personal project.)
This! The carpe diem mentality has always had this flaw IMHO. Humans are what they are because they invented ways to deal with the future: being a good sport, a sense of community, trading, etc.
