Well, you were a bit long winded in your post, so I'm going to take the same liberty. I biked every day for a year solid, I live in PA, so I had a winter bike with studded tires, my work at the time was 7 miles from home, or 10 miles, depending on which building I was in. I did it, I felt great, I have a bit of an obsessive personality, so I was biking all the time, and feeling great. Then my job changed, and I started doing it just a little less, but hey, I was still doing it, so that's all that mattered. Then it changed again, and I was doing it less. Then I got a different job, and my distance went from 7 to 10 miles to 20 one way. When I was cycling every day I would have LOVED a 20 mile each way ride, but when I switched jobs, and tried the commute, I found that I was far, far out of shape, oh, and look at that, I had gone from hanging around 230-240lbs (which was the result of many many miles of bicycling, being as when I started I was 299) back up to 270. Well, I started the new job, it was just tooo hard to bike in, and I had other constraints, blah blah blah.
So, here we are today, I started back by doing some park and rides, where I would drive a little over halfway, then bicycle in. Now just this Tuesday I did the whole ride, and it felt awesome, I was in a great mood all day, biked home, and I loved the ride home all but the last about 3 miles. For those 3 miles I said all kinds of NSFW words, and my legs tried to pull themselves from my body with the intention of kicking me till I learned my lesson of what a stupid idea this whole biking thing was. Then I got home, and my entire body decided to forgive me. I felt great again, and had zero regrets. I plan to do the complete ride again tomorrow, and hopefully next Monday as well. Soon I'll be back to doing that ride more often than not.
I can't exactly tell you how I went from getting over 3,000 miles a year for 4 years straight (one of those years getting 4,600 miles) to getting less than 500 last year. I'm not really sure what the hell happened, but I can say now that I'm back at it, I plan to do my best to keep remembering how great it makes me feel, and hopefully I'll be back down in the lower half of the 200's soon in weight. I'm currently hanging around 276, so not as bad as where I was when I started, but still a far cry from where I'd like to be.
I hope this helps, you're not the first guy to gradually just fall out of it, neither am I, and we won't be the last ones either. What we can all do is make sure we keep coming here and helping one another to not have that happen again.
Happy pedaling!
Joe