Saw this on Pinterest, thought it might be appropriate:

Nice one!
The sad thing is that some people actually do just that.
We had a topic here in the hugs folder a couple of days ago from someone who was snapped at by a stranger: "What do you have to smile about?" this "gentleman" asked her.

Seems like to some people we just can't do good. If we're sad, we have not enough reason to, and if we're happy, we have not enough reason to, either. What are we supposed to do to, just walk around emotionless like robots.
OP, as for "counting your blessings": I force /myself/ to do that sometimes, but I would never tell someone else to do that. I'm all for gently trying to help a sad person look on the bright side of life, but not in a condescending and dismissive way, because that is indeed much less than helpful!
You would be totally within the right to call this lady out on her dismissive behaviour and explain to her why her attitude is not helping you at all. Gently. I'd approach it from a positive angle, voicing that I know she is probably trying to be helpful; but explain why it doesn't help at the moment.