I had not ridden in a long, long, long time and my first ride was like 6 miles, sevearl rides at 12 mi, then 20 and then I tapered back down before hitting 30 and then a 42 ride and then tapered back down and basically did a back to back 50-60 milers on the weekend before 200K but this ramp-up was over a 6 week period with consistent riding and timely rest. I thought I pushed it very hard and no way I could have done 40 miles out of the gate. Maybe back off and build up a little slower? Unless you are very young and cross train.