Excuses or valid reasons?

I've not been on my bike in too long. Mostly it's been because of the number of hours I've been working. The secondary reason has been weather but I'm starting to question whether the weather has been a valid reason or if it's just been an excuse. Has it really been to hot or have I just been lazy and fearful of what my next ride means?
I keep saying I'd like to try for 50-60 miles on my next ride. That is scary. That is 6 hours worth of time. That's stop to eat and refill water and drink riding. That's only half of the amount of mileage I’ll be fighting to complete in September. What if I fail? Am I afraid of failing at 50 and discouraging myself from the 100 or has it really been the weather?
So I looked back to see. I noticed that most of the days I had planned to ride had random thunderstorms. The others had 100+ degree heat indexes. There were very few I could have actually ridden safely and sanely, Especially that many miles at my level of fitness and experience. So was the weather a reason or an excuse?
It was a good reason to make an excuse because honestly.... I'm afraid to get out and ride and fail and let myself and everyone else down.