I am 3 1/2 weeks post PLIF ALIF 360. I find that I am still so weak! I take a shower and I'm exhausted! It seems that anytime I get up and do anything to exert myself, I get weak and shaky so easily. I am in good physical shape but I'm so tired! Is there anything I should / could be doing to get my endurance up? I want to get going again!