You may be ramping up too quickly. It doesn’t need to feel like torture. Drop any preconceived notions of what counts as an “exercise session”. Go as slow as you need. Let your body adapt.
When I first got back into running 2 years ago after a long hiatus, I had to learn the painful lesson that I was being way too hard on myself. I eventually figured out that I can slow down and start with just a very slow 0.5 - 1 mile jog. I can even stop and stretch in the middle of the run if I'm feeling tight. It sounds silly, but I didn't realize that was allowed. There are no rules. If anyone judges you, that's there problem. You do you.
Here’s one of many, many possible examples:
* Walk for 10 minutes 3x a week for a few months.
* Walk for 15 minutes 3x a week for a month or two.
* Walk for 20 minutes 3x a week for a month or two. Stretch for 5 minutes before or after walking.
* Walk for 5 minutes, then jog VERY SLOWLY for 5 minutes, and then walk for 5 more minutes. Stretch for 5 minutes before / after.
* You get the idea…
And if running isn’t your thing, try something else. The only that matters is that you move and use your body. There are a million ways to move the body! I bet you can find one you like :)
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More philosophical / technical approach:
Treat it like a puzzle. You have a System in State A (your body and your current behavioral patterns).
How can we get the System to State B? Or wait, perhaps State C or D are just as good or even better! We just didn’t realize those were possibilities.
Consider dropping old assumptions. Experiment! Try different things :) What are different ways of interfacing or evaluating the system? Perhaps some of the old interfaces and metrics aren’t as useful or applicable to the current state?