Adding to the armor topic, training with armor is important to. Your shooting stance and the way you move is changed to maximize the armour's effectiveness. I have both, soft for work, hard for a very bad day, and you will notice a huge difference in weight. My duty rig for work adds about 30lbs, belt/armor. The bad day rig is SAAPI plates, and loaded for bear is around 45lbs.
It's hard on the knees till you are used to it or pt to prepare.