Hi Emily,
Good question. I like to divide muscle aches into 3 sub-types:
1. Pain - Whenever there are sharp pains somewhere in my muscles (or joints), I treat them as signs that there may be an issue and I take (at least) a day off, until it is over. Here I'd rather err on the side of cautiousness (I recommend that to anyone). I did do this a few times in the last months, but not a single time was really alarming and it was always over in a day.
So, simple rule: pain = no exercise.
2. Tiredness/slight soreness - when, after (the day after) exercising your muscles are not as powerful as on normal, and as a result it's slightly harder to move. I wouldn't really call this pain. This soreness is stronger after I have exercised a few days in a row, and when I know I have I allow myself to take a break day. My overall policy is to have 1-2 break days in a week. If I feel sore, but have only exercised one day in a row, don't skip, but but I go to the gym and exercise either a bit shorter, or (more often) I do a different combination of exercises, using different muscle groups. So, one day I may do a 12 km run, the next day I may do 30 km of cycling and 5 km of rowing, and then I may do 6 km of running and 10 km of rowing. I basically rotate between different exercises, a bit like cross training.
Lastly, I try to build up my exercise routine very consistently. The only real injury I got in my life was after I jumped from 40km of running per week to 60km per week (a few years ago). Had an injury for 6 months (turned out there was another reason for that, I have very flat feet (insoles solved that issue), but I am sure that this sudden jump in my exercise routine contributed too). Now I only allow myself to increase my distance (for any sport) by a maximum of 10% per week. If I have a big jump (let's say a competition), (if possible) I anticipate it by taking it easy for a few day, and I take it easy a few days after to rest.
My rule here: muscle soreness must be managed.
3. DOMS (delayed onset muscle soreness) - This is the extreme muscle soreness that you get after doing a new kind of exercise, or doing something you are already doing on a much higher intensity. The most intensive DOMS that I have had was always after sports competitions as a student... when we would do more than 10 different sports against other teams, and go all the way for it. The next day you may be fine, but then one day after that I sometimes can hardly walk!
I try to differentiate DOMS from normal soreness, as this DOMS can be much heavier and I don't want it to discourage me (because, after exercising consistently for a few months now, I don't have a lot of DOMS anymore) and just take the rest that I need and get back to exercising when it has passed, or I do something that does not require the use of those muscles very much. Light exercise can be very helpful to reduce this. I read in your journal that you often do new exercises, and so you may often have this DOMS. Just remember that this is the exception, that if you do activities more often that it won't be nearly as painful as after the first one or two times.
Overall I can say that I don't really struggle with muscle pains. A bit surprising, at least to me. I actually like feeling that I have done something. I trust that my system of using regular break days, consistent training, body awareness (responding to pain by taking breaks) and cross training helps to prevent injuries.
Finally, I also have muscle soreness today, but I will walk to the university (1 km), moving my body a bit already cuts my muscle soreness in half (the soreness is the worst after waking up, when your muscles haven't done anything).
I will work there for a few hours and then I will go to the gym. Will do 20 km of cycling, 5 km of rowing, and in the evening I will do a 7 km run, everything on a moderate pace. Tomorrow I will just cycle 15 km at the gym (slowly) and do 2.5 km of rowing, which I count as taking a break day (one reason that I still go is that I get 1 euro discount for every day that I show up at the gym
).
