Thanks, Pete. I would say I'm an in-between stage of you and your wife.
I love statistics about myself (2.03 peak K/D in Call of Duty!) so I enjoy tracking calories on Myfitness. I use it as a rough guide and it has helped me to 'eyeball' portions and accurately estimate calories but I do it every day day in day out. I also use runkeeper to track my runs and rides.
For exercise, I've always been about cardio as I'm not physically very strong and hate lifting weight. My goal is always to get trimmed down, burn through the miles at a decent pace (for me) when I run and develop a super strong cardio engine.
Given your appreciation of statistics, performance tracking, etc, I would strongly urge you to give Fitocracy a shot (or another shot if you've tried it and lost interest). You input workouts and receive XP based upon your performance. You earn badges for leveling up and can even go for achievements, for example benching your own weight (as you've mentioned later in your post). Cycling, running, P90X, strength training, it is all included on the site. If you decide to give it a try, I'm PeteRock over there as well. Just click the "follow" button and you'll have access to all of my workouts, stats, achievements, etc.
Now that I'm into biking it has compounded the exercise benefits as I cannot consistently run with joy (seriously, one bad outing can make me quit) and because of the punishment it causes. So I have rotated cycling in to keep me motivated and fresh. I only have to run 2x or 3x per week now and I mix in one or two giant bike rides (for me 18-25 miles at approx 3:50 to 4:10 per min pace) per week.
It's great to mix it up. It keeps exercise from becoming a chore, and cycling allows you to cover far more ground than running. Plus it's much lower impact on your joints.
The problem, like you described, is I'm either ON or I'm OFF. If I'm in, I count calories and make exercise a point. If I'm off, I am a glutton who eats at all hours a day just to do it and I don't do anything. This leads to depression and eventually disgust which gets me started on the road back until I get there and quit or quit along the way.
I know this cycle all too well. Usually it's an injury that sidelines me, and when it does I immediately want to hork down cheeseburgers and garbage and fall into that "if I can't lift then what's the point" mindset. I like to consider myself of strong will and determination, otherwise I wouldn't be where I am with fitness, school, etc, but I still sometimes fall victim to lapses in drive or consistency. The key is being aware of it, and rather than giving in, the hard part is saying, "No, not this time."
Maybe the solution is there's no middle ground and I always have to be ON, but not punish myself if I have a bad run or a day where I consume more than I want to.
I've tried to take that to heart as I've had two very bad runs that I've persevered through with the simple truth of: the goal is not your time on this run. Your goal is to get back to 180lbs (and be fit and live longer etc). And it worked. The nice thing though is that this time around I've layered in something new: biking.
Think of it this way. Are you always on your game at work? Are professional athletes always flawless in their competitions? Are you always top dog in COD? No. Everyone has bad days, whether at work, on the softball field, on the basketball court, in a COD match, and some people are occasionally surprised to learn that the same goes for workouts. It's simply a fact of life. It is impossible to turn in your best workout for each and every workout. There are just too many variables. Did you eat enough, or too much, did you get enough rest the night before, is your body sore, did you train too hard the previous day, is your mind wandering, are you stressed, did something upset you, are you distracted............These ALL influence your workout. And that is in no way grounds for discouragement. Hell, before neck surgery I was deadlifting 265lbs. Now? I have yet to get past 185, especially after a severe back strain in late April. Before my trip to Costa Rica I was squatting 225. Now 205 is tough (for reference I'm not talking one-rep-max, I'm talking 5 working sets of 6-8 reps on all this).
We all have bad days, in almost anything you can think of (video games, work, relationships, etc). Workouts are no different, and surprisingly a lot of people for some reason don't make that connection. You can't be at the top of your game 100% of the time. The key is not to get discouraged, to understand this fact, and overall a shitty workout is better than no workout at all. There's always the next one. And the next one. And the next one.
When I get back to the 180s (I'm 6'0) I am hoping to find the time and $$ to join a gym for lifting.
There are also some cool books on bodyweight exercises for strength training, eliminating the need for a gym altogether. I just prefer to use weights as I enjoy strength training. I track every single workout, every pound lifted, every exercise completed, both in a journal and on Fitocracy. I get to track my progress, to see where I left off last workout to push me to lift more this workout, I see what exercises I've done and perhaps decide to change things up on occasion, and I'd be lying if I said the XP on Fitocracy wasn't a strong motivator.
My one great fitness goal (I've done two marathons and am eyeing triathlons but am a terrible swimmer) is to benchpress my own weight. I've never even come close, not even when I was getting really strong in college. If I can do it by 40, (18 mos from now) I'd be completely over the moon.
A very realistic and achievable goal. Most of my life I wasn't able to do so. The day I finally did was an achievement I had pursued for years. Then it became squatting and deadlifting more than my weight as well. Then it became benching my weight in dumbbells rather than just barbell. Then it was 1.5 times my weight in deadlifts and squats. There is always a goal, always something to work toward achieving, and the best part? Throughout the process you're always making yourself better. You get stronger, improve your health, improve your appearance (people who insist they ONLY exercise for good health are typically lying, we all want to look better because it improves confidence and how you feel about yourself), you become more confident, your self worth improves, and you perform better in other areas of your life.
Don't let bad days discourage you. They happen. Just like in COD, sports, etc. I always feel that a bad workout is better than no workout, and my next workout usually improves considerably. My first week back after two weeks of vacation was rough. This week? It's good I dressed in black because I killed it.

Get some.