Feeling sad

My husband and I have been TTC for about 4 months now. We're both 33. I know that's not a very long time, but yesterday one of my co-workers announced that she's pregnant. She said they weren't even really trying. They conceived in the first month she was off the  pill. I'm really happy for her, but it kind of made me sad. 
I feel like so many other people are getting pregnant a lot faster, or while they're not even trying. 
Feeling really discouraged! Anyone else feeling this way?