Novelty in Heaven

We have mentioned a few times in class that once you have something that you want, you don't want it anymore. You can spend years waiting for a brand new cell phone, once you have that cell phone for a year you will no longer be as enthused about it. It occurred to me many years ago that this same principle (which Dave Kenneth Johnson mentioned in class, though I've forgotten the name) does very well apply to heaven. 

Heaven, so I've been told, is a place where people who have spent their lives obeying the Christian god's will have the privilege of continuing to obey and praise god for all of eternity. In addition to that reward, you get to be eternally happy, having everything you could ever want (except for maybe the love of your friends whom did not obey god). It seems to me that two things could occur here. The first is that your mind will be altered to make you find this after-lifestyle more agreeable, that you will always be content; in which case, you are no longer yourself and therefore reap no reward. The second is that, after spending 3 billion years of your newly eternal life, you find yourself unable to be satisfied with heaven; you would be completely unhappy with that life because the novelty has worn off. Sadly, however, you could not end that life, because it is eternal and because in heaven, you can only do good wholesome things, like obey your god.. Thus, that which you previously identified as heaven becomes more like hell; which is not a reward.