Good. Just, for me at least, has to be in moderation and at the right time/s. It does seem to help me sleep a bit better, when I've expended some energy in the day but it can also, if too close to when I try to fall asleep, keep me up and alert for longer...
Definitely, to even just get a few miles each day of walking, can make a dramatic effect, versus not hardly walking or doing anything day after day; getting a bit of daily sun, goes a long way with that, too. Also, I think that doing minor/basic stretching of the limbs with slow breathing (sort of meditating doing such, just focusing on body and counting), can make a dramatic long-term and broad effect.
The two things above, I believe, combined with diet (gluten/dairy free and moderate meat consumption, all organic/local only) have made the biggest impact on bettering everything, and especially my Cataplexy. One thing though is I can't necessarily say that it has eliminated EDS, as I actually may have more of such, than prior; but I do have less headaches/fatigue/weakness and HH, yet I dream near the entire time I sleep it seems.
Running is something that is hard for me, I'd do it more often because it is super good for the body if one can manage it, but it for me results in headaches, just as riding a bike for long does as well.
Through my childhood, teens and a lot of my 20's, I did a lot of physical/sport activities, near every single day and for many hours most of those days.
Now, I definitely can not manage more than perhaps a few hours here and there, maybe a few days a week if lucky. Most weeks, I may get a total of three or four hours, of actual more intense exercise.
Skateboarding (all year) and/or playing ice hockey (during winters) are what I enjoy doing the most (which is a huge part of being motivated to do any of it) but it is too easy for me to go overboard, get carried away and then, or later, find myself with a bad headache or days of such with aching; that's with or without injury from said activity, I don't always fall skateboarding and I don't play hitting hockey, although there are the occasional collisions.
The Cataplexy doesn't tend to impact these much, these days thankfully (fingers crossed), but when it is there I have to be extra extra careful, avoid it and/or stop.
Skateboarding triggered,or triggers, Cataplexy from landing the tricks that I really want, or from others reactions/hollers/smiles (all emotion combined with adrenaline).
Ice Hockey triggered/triggers are more to do with being so exhausted and/or weak, the Cataplexy can interfere on a break away for instance, or receiving/sending a quick pass.
For me, Cataplexy doesn't just happen though, without some triggering; unless I am somehow at times not actually picking up on some effect of it (which I must say is very common for me [did that for years and years, adjusting naturally/willingly, attempting to 'not ignore' it, but adjust with or to it, to just let it be and dissipate quickly] I may not actually note something which I should be able to note, it is afterward once I've reflected, or it's been pointed out to me, it can be sometimes shocking..).