I ask myself that all the time. Lots of days, instead of feeling energized by working out, I just feel relieved it's over.

Biorhythms. Or, y'know, not.

Stress, attitude, mood (how much endorphins you already have goin'), sleep and food schedule, where your muscles are in the recovery cycle..?

After a nice coffee date with a ladyfriend I've run five miles effortlessly and at a crazy fast pace, while on other days I've plodded through 2&1/2.

Wish I knew, s_r. I just chalk it up to my body being angry at me.

When I was running (sob! stupid center of gravity changes!) I had exactly the same thing happen, s_r, so I'm damned if I know why, but I daresay it's pretty common.

stress. overtraining. central nervous system fatigue. lack of sleep.

those are the only ideas that come to mind.

when i lift, the perceived weight of the olympic bar tells me what kind of workout i'm going to have. when the bar feels light, i know i'm gonna rock the house. when the bar feels heavy and awkward . . oh, boy, this is gonna suck.

do you notice any such signs, messages from your body, on those off days?

Some days you're the bug, some days you're the windshield.

j_p- yes but I usually blow it by doing something like running extra fast when it feels easy. Then I burn out early.

I suspect today was great because easy day + slower music = reasonable pace.

On the hard days? I have no idea. Sometimes I have to just give up after a couple miles (and then feel like a loser the rest of the day) and others I can chug through my usual routine but at the end I'm as red-faced sweaty and fatigued (and high) afterwards as if I'd done a really hard workout. (So it's not all in my head.)

I hope to figure out how to minimize the bad days and so far I haven't figured out the formula.

It took me a long while to figure out that things were always going to be hard 2 days before my period, so my observation skills aren't all that. But I've been trying to journal everything and so far no revelations.

I figured you exercise-knowledgeable bunnies might have some info I'm lacking. Actually it's inevitable since no one I know does anything besides basketball and surfing. I'm the only exercise weirdo around here. My exercise knowledge is about zilch.

wow that was really long. sorry.

You might not be eating enough for the level of activity you're doing. My aerobics days are tough and I have to eat quite a bit or I crash hard. See what I askmefi'd recently.

If you're workday is stressful or physically tiring, you can try a little bit of caffeine on the days you feel wound down. See if it helps. Note: I am NOT saying down four Red Bulls and, please, no Red Bull and Vodka.

Sometimes you can be fighting a virus or infection, too. I had a very minor touch of bronchitis a couple of years back and it wrecked my routines. (Lung stuff is particularly tough and you really shouldn't be working out (at least aerobically) with a lung issue.)

Another possibility: You're not drinking enough water and are somewhat dehydrated.

These are all the things have impacted me. My workouts are regular and, at times, tough. (Bastard trainer from hell.)

I've often wondered this, too, but I've been at it long enough that I don't worry about it. Take the great days as they come, and just do your best on the off days.

Sometimes the reason is clear, as you see - for me, not enough sleep, stress at work, meals. A big starchy lunch will make me start dragging every time. Sometimes I think maybe I'm not eating enough protein, which you need to keep repairing muscle if you work out. Sometimes I think maybe there's not enough glycogen available in my body. If I'm breathing shallowly all day (related to stress) I feel like there's less energy there. Sometimes maybe the body's fighting off a virus or bacteria and reserves are going elsewhere. A lot of times I blame dehydration, unless I'm really sure I've had enough water. Tiredness is definitely a symptom of dehydration. Menstrual cycles definitely make a difference. Pace makes a difference. Mood and weather make a difference.

Just chalk it up to what makes life interesting. We're more complex than an internal combustion engine, and even those are affected by small changes in fuel richness, temperature, and moisture. Why not us? Definitely diet and rest and all that can minimize the number of off days, but if you're already doing well on those fronts and have no other noticeable medical issues, I'd say just roll with it. Even elite athletes have good days and bad days, even ultramarathoners and cycle racers and Ironman competitors. I think it's just part of being human.

When you complete a workout on an off day, even if it's really hard, you get to feel more proud of yourself for sticking through it, though. So definitely give yourself more props on lousy days. You're still out there moving faster than most people.

Even the local elite runners here have "dogmeat" days, as they call them. Something that you just need to train through. The skill is knowing how much to push it and how much to lay off.

One of my coworkers went for his usual noon run, a few years back, and fell dead of a heart attack. I have always wondered whether he felt really bad, and just told himself to push through it, or what?

As a result, I will usually back off if I am feeling iffy, on any given day.

Lord, danf! I refuse to worry about heart attacks when I do my slow poke morning jogs.

Thanks, y'all. I guess I'll just try to work on having fewer dogmeat days and not worry about it.

It's nice to hear it's universal, though I was more hoping for something to get rid of them altogether.

Oh GOD! Don't worry about heart issues while you're working out. I have heard some very hard stories. Listen to your doctor when it comes to that stuff! ;-)

One of my coworkers went for his usual noon run, a few years back, and fell dead of a heart attack.

I've known two people that something like this happened to - one while running, the other during B-Ball, both under 45. But in both cases, it was totally sudden, not preceded by feeling bad during the whole workout. It seems that there are certain people in the population whose tickers might just do this due to a pre-existing condition that is triggered by the exercise. It doesn't seem as though it should prevent anyone from exercising, though, as a sedentary existence also carries risks of heart illness.