I think that's a really good Q. I've said this before & I'll say it again... while having a lot of negative thoughts (fear, anxiety, etc.) can inhibit the onset of labor that doesn't necessarily mean the reverse is true! I.e. I do NOT think that readiness/ positive thoughts brings on labor any sooner than, say, a neutral outlook.
Baby's come when they are ready. (Well, if they are healthy & all is well - we know sometimes something is "wrong" with prematurity, etc.) Anxiety can stall things, but not delay forever (the most anxious women in the world is going to pop sometime!)
I think the same is true with pain - a high level of anxiety can increase the level of pain in labor, but that DOES not mean that the most optimistic, fearless outlook will guarantee a pain-free birth!!
As for my own personal comparison, I exercised a lot through my pregnancy & Dr. Clapp's research (basically the only one to study exercise in pregnancy!) shows that 75% of exercising women give birth before their due date! (Although he didn't clarify which were primi vs. multiparas (had given birth before or not.)
With exercise & the fact that my sister went early & my Mom & G-ma went right around their due dates, I was CONVINCED I'd go around 38-39W. I had no fears except a little anxiety about the hospital (planned to labor at home as long as possible.) was actually looking forward to giving birth! Was ready at home, ready to leave work, etc.
I never had a SINGLE contraction until after having my membranes stripped at 41W4d. (One during an NST that was so minor, I barely count it. And that was ONE, just ONE!)
Yup, I was 'ready' emotionally & in terms of baby 'stuff' etc. at 38W & that boy hung in until 41W4d! So, there you go. Ha!