I'm still a young man with good feet, strong back and in relatively good health. My Bible describes two appropriate bodily positions for worship. Nowhere in my Bible does it talk about sitting before God. I recommend that you spend time in both positions. When you're at home alone, prostrate yourself on the floor before God and learn what it is to cry out to God and make an appeal unto Him.
Position has a lot to do with out attitude.
Standing is a universal mark of honour. We give performers standing ovations. When I analyzed why I don't like to stand it boiled down to two principle realities. First, I have an inadequate vision of the blazing glory and majesty of my God. That's why I don't find myself compelled to stand in Him presence like all the host of Heaven are.