Silly but I have to get it off my chest

Sometimes, say this Monday, when I arrive back to the office after doing deliveries, and I see that there is 26 or 30 messages all waiting to call back and book in - do you get frightened by the sense that you may be succeeding? I've found recently more and more, I get quite anxious and panicky, thinking oh its all going so well - so it has to stop! something will happen and its all going to fall down, or I'm not going to be able to manage it all on my own and I start to get really stressed. I do worry that my workload is getting ridiculous, but then some days like today, I only have 4 customers to see and I think its all ok again.
So does anyone else's mind play tricks on them? Do you fear success sometimes?

Yes all the time but my issues is taking the next step and knowing that it will all be ok. I am scarred to stop my part time job in case things slow down and then I have nothing. I have such a great workplace (been there 10 years) and extreamly flexible arrangements (I come and go as I please and work my day around my deliveries!)
But at the same time I know I can't keep doing both as it is starting to affect me and the family.
I need to keep believing and take the jump

Not silly at all!
I think everyone gets a little freaked out when it becomes overwhelmingly busy.
For me, I found it sometimes a little scary because of the nature of the business you cant let people down or not show up or do things incorrectly because you are so busy.. the pressure!