What is the best way to train for doing 3 days in a row? I am doing a charity ride in June, and I can cycle 70 miles, but I haven't ever done it day after day.

The tour is as follows:

Day 1 - 70 miles
Day 2 - 70 miles
Day 3 - 50 miles

All I ever read is "ride and recover", making sure your body is correctly fuelled and given the longest amount of recovery time. All the basics really.

Is the trick just fitness - ride 100 miles as often as possible, and that will make 70 miles seem easier on the body?

ANY ADVICE WELCOME - if you've done a 3 day in a row ride, please tell me your hints, tips and experience.