Plenty of great advice here. I especially concur with post #11 and #19.
See my tips on this thread (
url).
Whatever tiny little light you do experience in a meditation - be it your happy thought, or an energy sensation that is interesting to focus on - grow it. Focus on your highest consciousness and make it bigger.
It will grow, because we are programmed to evolve in the light, to expand. And the Universe gets excited when we deliberately try to. It will send the angels to help. When you take one step towards the light, the Universe takes 10 towards you.
Negativity comes up in meditation to be detoxed, purged, dissolved or transformed. It's supposed to come up - much like a healing crisis during a fast. So don't despair. Keep trying - whether in sitting meditation or out there in activity. The benefits will come. After the storm the sun always comes out.