You should be able to do SS with that level of activity. What is your height/weight? Describe a typical days worth of eating. When in the day do you work out? Are you getting some Pre workout carbs? What's going on with your post workout routine (shake, carbs, BCAA's, etc). Are you taking creatine?
It takes a bit to get used to standing a lot but you should get used to it in a week or two.