I've never even come close to having a problem when responsibly wearing ONE earbud (I'm never drowning out any senses), so I bring music and podcasts with me on long rides. I find (long) podcasts that are engaging pass the time very quickly (like the hour long NPR or half hour How Stuff Works shows); music that I know actually starts to drag me down after like hour 2. I never ever stop along rides unless I really need to for a refill or defill or something, but I know some people will plan in a coffee shop or something halfway; not my cup of tea, but you can if you want. Also, putting your head down an TTing for 5 miles, and then cruising for a few miles just looking at the scenery also helps tick away the miles for me. The end of long rides are also great times to work on things like form and pedaling that usually fall apart when you're tired and it's something else to keep your mind on "circle circle circle circle..."