Sit to RIse test predictor of early death? Can you do it? I can't!

I'm trying hard to exercise more, reduce my weight/BMI/cholesterol and become healthier. I've been watching the recent series on ageing well (the one with Angela Rippon and Dr Van Tuelleken) and I'm still freaked out by that sit-to-rise test which I can't do. How worried should we be if we can't manage it without supporting hands/struggling ? I know I'm not fit but I exercise more than I used to do...(twice-weekly gym visit which I know isn't enough but it's a start)