I try not to let what people say affect my writing or motivation to write. I won't say it hasn't happened before, but I can't remember the last time it did. For the most part, I write for my own enjoyment, and as long as I'm happy with my writing, I'm satisfied. I know the kind of stuff I write doesn't appeal to everyone, and that's okay. I also know there's an audience out there that does like what I write, and that's a nice perk.
Generally, the things that keep me from writing or wanting to write are the same things others have mentioned - lack of time, lack of energy, being hungry, not feeling well, stress or too much on my mind, etc. I write best when I am well-rested and have a whole day of no commitments or responsibiliti es ahead of me, and unfortunately, that hasn't happened even on weekends lately. Well, except for today, but because this is the first day all week I've had to just lounge around and not do anything, I want to do just that - nothing LOL. Not even writing. Sometimes writing just takes too much brain power LOL.