My workout plan has finally settled down into something approaching a routine. I try to work out every day but I don't always make it out -- but that's fine. I achieve the goal -- to work out five or six times a week.
The center-piece of my workout plan is one day of intense exercise in the gym, following the workout plan mentioned by Timothy Ferriss and described by a few others. The essence of this strength-training workout is One Set to Failure: prefer compound movements (not muscle-isolation exercises), take a long time (five seconds or more) to perform each rep, and pick a weight where you can do 6-8 reps. The last rep should be to failure. Not just "I want to stop" but "I can't go on!"
Another key is to not over-train -- this intense workout should only be done once every four days, or possibly once every week or 10 days. Definitely don't work out every day; even every other day is too much. The idea is to avoid stress hormones. After such an intense workout, your body will respond, but constantly stressing it cuts off some of that response. You don't need to work out every day to build muscle. My days are busy; I don't really want to spend an hour in the gym every day. The only reason I would is if there's substantial gains there, and the research that these guys have dug up suggests that training more than once every four days produces a decrease in results.
A few people in the paleo community suggest fasting on this day, to pump up growth hormone levels. That might work, but I still haven't settled into a good fasting schedule.
I typically ran sprints after this intense workout, but over the last couple weeks I've shifted it. It might be a bit counter-productive to try to run hard after this workout since I've already stressed by legs pretty hard and they tend to be rubbery. Either way, my running schedule is one day of Tabeta sprints, a mile jog, a long walk (3-5 miles), a mile jog, and then repeat.
Tabeta sprints are sprinting hard for 20 seconds, resting for 10 seconds (true rest, not just walking), then repeating. What I've read on the procedure suggests doing eight such sets. So far, I'm up to five sets -- I'm just not that fit yet. :) My mile 'jogs' aren't really jogs, either -- I tend to run about half the distance and walk the other half.
I've noticed considerable improvement in both strength and fitness over the past couple months. My weight hasn't budged in that time, but I don't have solid records on body fat. My pants are definitely looser; I've dropped two inches there. So I'm burning fat, but I'm making up for it in muscle gain. Running has also gotten easier. The first time I went for sprints, that third set was painful. I'm now doing five sets. (The Texas heat isn't helping!) Likewise, my jogging days started out as walks, and I'm up to jogging a half mile each time. (Walk a bit, jog a quarter mile, walk a bit, jog a quarter mile, walk home.)
Improvement is fun, and I'm seeing it. My roommate really wants to work out more often, but I'm not biting. I'm getting results with this program, and I'd be tempted to tweak it, but I'll wait til I hit a plateau.