Protein needs and other Foods

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Hello all- I was just wondering if anyone had any suggestions for finding out how much one ACTUALLY needs for daily nutrient intake, like protein? While I'm good at tracking my food intake on MFP, I have been advised that their recommended protein goals are rather low for someone working out and weight lifting routinely.
So how do you KNOW how much you need?
AND how can you change your daily goals on MFP so it doesn't make it a bad thing if you go over?

Thanks all!