Thanks - I find rest hard, but Steve A's description of the need for rest for adaptation rings true albeit at an infinitesimally small level compared to his. I've felt like I'm grinding to a halt, not getting fitter.
Comparing yourself to others and thinking you should be doing more, when YOU should be doing less is an easy trap to fall into IMO. My daily mileages last year were small beer to what I can do on a standalone day. I was never riding hard, because I wasn't able to and even if I was, one hard day when I had to keep going for a year would have been overdoing it.
Likewise, I've started training with a coach. My training is based on my limits, not my expectations nor what other athletes are capable of. Also what I do is based on the current situation.
I abandoned my training ride on Sunday because my power output fell below what I was aiming for and I felt off. I eased right off and groveled to the nearest town, where I threw up, then checked into a hotel. I could have ridden home but it would have been very tough and done a lot of damage that would have taken a long time to recover from. It wouldn't have been any benefit to my fitness. I would have done if I had a job to go to, then spent the rest of the week recovering. What I did was to rest up ASAP and recover as fast as possible so that I could resume training. The following day, I was scheduled for a rest day anyway so I took that, then the next day I got straight back onto my schedule and did a good day, considering I couldn't prepare for it as well as if I were at home.
I also cut last night's ride short. I did a turbo session in the morning and did the toughest option my coach gave me. I could have done my full ride last night, but it could very well have been to the detriment of today's ride. I may even still have to take the easy option today because I am still tired from the turbo session, then I have a rest day on Friday. If I find today easy, then I know to go a bit harder next time. I'm still tired and will need a recovery day, so I'm still getting ahead. Riding hard too much just sends you backwards. As Michael Hutchinson once said, make your hard days hard and your easy days easy otherwise it all becomes a constant mid range effort and has a lesser effect. Doing the easy days is often the hardest thing.
I like what FBOAB said about there not being overtraining, more a case of under recovery. Its the recovery that gets you fit. If you're unable to meet the target, then it's probably because you've done enough already.
The other saying I've heard is that anyone can train like a pro, but we can't recover like a pro.