How can I get rid of the lactic acid build up in my legs?

Yesterday I ran the mile and now my legs are very sore. I was told by numerous people that its (probably) a lactic acid build up. How can I get rid of this?

I know salts in a bath but, we don't have any and i tried it before and didn't notice much of a result.
Update: For some reason I thought walking was helpful! Glad to know it helped and not made it worse.

And I can walk normal just a little soreness.
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