Muscle Fatigue/Pain

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First, super sorry if this post has been made over and over- I did a quick search but didn't see this topic.

I played roller derby for 6 years, which created leg strength and core strength, but my arms have always been sort of meh.

I blew out my knee and had to have surgery last year and could never really push myself in derby again for fear of getting hurt, so played half-assed for another 9 months before quitting. I gained some weight, quickly got out of shape, and decided in March to get back on it. I'd been doing some dieting, and some half-hearted lifting, but decided to kick it back in to gear and started the Jillian Michael's 30 day shred yesterday.

I really pushed my legs on the squats and lunges and woke up this morning with that "good" muscle pain (I worked out, it feels great). I did day two today and am already feeling the fact that my legs are going to be pissed tomorrow, even though I dialed it back a little today.

How do I preempt the pain I know I'm going to have tomorrow?

Thanks! And sorry again if this is a duplicate/overdone post.