Give it LOTS of time! I'm not sure, but I think P90X is progressive, meaning it's only going to get harder! I teach both fitness and pole classes and I'm in a constant state of soreness!!! Advil helps a lot. Make sure your stretching out REALLY good after you work out and get yourself a foam roller ~ They work wonders!!! Also, drink LOTS of h20 and eat plenty of high-quality protien to help heal rebuild those muscles! Soaking in a warm bath with Epsom salts helps too!
List of high-quality proteins:
Meat and Legumes
Eat a variety of high-quality protein such as lean cuts of beef, poultry, pork with visible fat removed. Also consume legumes with whole grains to get a balanced protein meal. For example, quinoa with adzuki beans, or millet with French green lentils or black-eyed peas with brown rice will provide complete protein.
Eggs
Consume high-quality protein by eating eggs, low- or non-fat dairy, soy and sprouted foods. Each egg has about 70 calories and seven grams of protein. To make a complete protein combination, consume eggs with sprouted toast.
Low-Mercury Seafood
Consume low-mercury seafood for high-quality protein and heart-healthy omega-3 oils found in fish fat. All seafood contains methylmercury as it is a byproduct of environmental pollution and is found in the smaller fish that larger fish consume. The EPA recommends eating up to 12 oz. per week of wild caught fish such as Alaskan salmon, canned light tuna, pollock or catfish. Limit consumption of seafood if you are pregnant or nursing.
Yogurt and Soy
A cup of non-fat, Greek-style yogurt has 24 grams of protein and 120 calories. A cup of unsweetened soy milk has about 80 calories and seven grams of protein. Pour soymilk over oatmeal for a high-protein breakfast.
I got this info from livestrong.com