Since my shoulders have been bothering me recently, I have taken a step back from climbing & some of my workouts to really focus on creating more balance in my body & address some form issues. I'm still working out hard, just in different ways, & am excited to share some of what I'm doing (even redeveloping some of my exercises, like my push up).
The body is amazingly complex, & minor issues can become overwhelming when you really start picking the anatomy apart. The body is more like a series of chains than a solid structure. Problems in one area tend to move up the chain & create problems in another area which move up, creating problems in another area... By looking at it this way, you can see how balance in the body begins at the foundation: the feet.
Not only are many of us on our feet a good portion of the day, we also love activities that demand more from our feet. Obviously we want healthy feet. Plantar fasciatis is an inflammation of the thick tissue (fascia) on the bottom of the feet. It is extremely painful & fairly common in pavement runners. Intense cardio & interval (body-weight) strength training also demand a lot from our feet (burpees, high knees, jump rope, jump lunges, etc.) Climbers tend to develop tight arches as well, which feel similar to those of runners. For some reason, it doesn't seem to develop into plantar fasciatis as easily though. I'm not sure why this is, but it doesn't mean they should be overlooked. While I've never had PF myself, believe me, it's nasty & can take a really long time to recover. Better to take care of your feet now than risk dealing with it later.
"Tight feet" also transfer to hypermobile or overly-flexible ankles, which mean instability. Plus, like I mentioned above, this could create problems in your knees...& then hips, etc. I started rolling my feet out regularly, because they get tight from climbing & my left ankle (previous strain) is constantly needing to be mobilized. Keeping my feet healthy makes my ankles feel healthier.
Very high arches are a sign of "tight feet". Notice how high Dave's arches are. His feet are really strong but could benefit from releasing the bound up fascia regularly. An easy way to do this is by rolling out the feet with a firm ball.

I like using a lacrosse ball. It is firm enough to hold its shape & get into those tight spots, but the rubber offers enough give not to destroy my foot. Rolling it out this way is nice, because you can control the pressure. You want to feel it releasing, but it shouldn't be painful. I suggest starting small -- maybe only a minute the first time -- & with less pressure than you can handle; assess how your body responds, & build from there. Everyone responds differently, so you might be surprised how much you feel the effects the next day. Also, you might not want to do it the night before a long run, etc. until you know how your body responds. Another point to keep in mind: often, tight arches stem from tight calves; be sure to follow your workouts with a good cool down & some gentle stretching as well.
Conversely, if you are "flat footed", you would benefit from strengthening your feet. "Weak feet" mean your ankles are taking up the slack, becoming stiffer, & are at greater risk of injury. If you wear really supportive shoes all the time, your feet aren't having to do much. This is one reason why some people are such fans of barefoot running. It forces your feet to be extremely involved again, & it can make them stronger. I have mixed feelings about barefoot running, but I think it can be a really good addition to your training if it is appropriate & if you are smart about it. This high-impact activity isn't the only way to strengthen your feet though.

An easy, silly exercise is laying out a small, hand towel, grabbing it with your toes, scrunching it, & pulling it toward you. Repeat until you have pulled the entire towel to your foot. Repeat on the other side. You can also pick things up, like marbles, with your toes.
These are simple things you can do while watching a show, reading, before going to bed, or first thing in the morning. I have made the habit of keeping my ball in a basket in the bathroom & rolling out my feet before bed, while I brush my teeth. This works for me.
I find when you are trying to incorporate maintenance-type exercises into your day/week, the best thing to do is find what works for you. Yes, there are probably times it is most optimal/effective on the tissues; but most important is that you just do it.
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*I am hoping to continue to share posts like this; they are only meant as a starting point for athletes & others to address issues in mobility & tissue. Use at your own risk, stop if it hurts, yadda yadda. Be responsible about your own body. Seek out a professional to work with you on specific problems. I have experience as a sports & injury Massage Therapist; most of what I share comes from experience, education during my mentorship, & a lot personal research & study.