I bought this particular NGI (the orange one on the left) and it was vibrant and robust. Then, one day I moved it to a very sunny spot and then it started wilting and just looked weak. So, of course, I moved it back in a shaded area and gave it a lot of water and within no time, it was lifted up again. However, now, although it's not dying, it still looks wimpy compared to what it looked like before. The flower buds are smaller, producing smaller flowers and the leaves are even smaller. Doesn't appear to be diseased, either.

I'm giving it plenty of water and it's in well-drained soil. Can the sun really do that much damage in just a few hours? It's been this way for over a week ever since that day. I shouldn't complain--it's still alive, but still...

What can I do to "revive" it?

BTW, this is not a before and after photo. Just slightly different shots with the lighting affecting the color results.

Thanks.