I realized I've been wearing the same few pairs of sweatpants since college (yes really) so I picked up this pair of lounge pants for $ 29. (katiesbliss.com)
You can have a special pair of sweatpants for your gym that goes with your gym accessories like the gym bag and gym shoes. (outfittrends.com)
They're so comfy and warm, like a good pair of sweatpants... just, er, on the lower leg. (glossyblonde.com)