Kevin,
Carrying the scope only counts if you do it for at least 30 minutes every day.

Feeling bad after exercise can happen if you haven't done any for a while but in your case, since you have headaches too, it may be something else.
Alex,
Yep, you gotta be fit for that round the world yacht trip. Surely you would have enough to do up there to get plenty of exercise anyway

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Dan,
I only tried skating once or twice, mostly hoping to meet girls (it didn't work). I think I'd find speed skating too scary. You just don't seem to have enough control or braking to deal with other road or path users.

The pleasure you get from skating reminds me of my 83 year old aunty who still swims every morning. She says that is her drug and she can't go without it. The pleasure is, at least in part, from the release of endorphins (?? or something like that) but that shouldn't start until you start to exercise. I'd say the pleasure you feel before starting is expectation of having fun - sort of a positive Pavlovian conditioning. Whatever it is, it certainly sounds good.