lol @ plan not to do it

I remember what helped me do a long ride, (the longest I've done is 100 miles), was a combination of

a) enough training,

b) thinking of it in little segments (like the next 5 miles and not 95 to go!)

c) getting into a rhythm, something comfortable and easy to maintain

d) as was said, just being in the right state of mind - maybe it is zen or something along those lines where you just hone in on a goal