If you don't walk, then you walk a lot, you're gonna get sore. Your legs will burn, making it hard to get to sleep. For me, I was okay with that. I'm old (as I may have mentioned). By the time you get old, you also get used to everything hurting.
Your legs are full of lactic acid from using up primary energy storage (ATP) and then using secondary energy storage--which degrades to lactic acid. As you use your muscles, your body stores more and more ATP, so you don't need to dip into reserves. Your legs will stop being so sore. This may take a while.
If the pain is gonna stop you walking, it's definitely preferable to start out modestly with, say, 5,000 steps a day for a week or two, and build up to 10K steps over the next couple weeks, etc. I can easily walk 25K steps and not get sore, even if they're largely uphill. But I'm used to it. You shouldn't attempt to do that out of competitive spirit, because you
will certainly pay and next day you'll likely crash and get very few steps at all--so, your body doesn't get the signal, and next time you'll get sore again.
With squats, etc., it's a double whammy because in addition to the lactic acid you will get muscle tearing. This also burns, and you need to give your body a couple days to repair the tears and in so doing, build muscle tissue. If you do not, you will keep getting more tears with no time to heal. You will break down--not build up--your muscle tissue. This is why people exercise different muscle groups from day to day.
So... exercise smart, not too hard. ❤