Accept
Having made a sincere offer, accept their answer. If it's no, they mean it, and you can wish each other a good day and move on. If it's yes, then allow them to guide you. They are probably expert at how they do what they do, and the safest approach. That means you don't have to know what to do, so you can relax!
How They Gain Mastery
It's best to start on the assumption that the person you have the impulse to help knows perfectly well whether or not they need help. They have access to skills and techniques in which they've been trained (in rehabilitation, at workshops, from others, etc.) or simply learned from experience. If they accept help, then they will guide you according to their mastery. People become expert thanks to the universal capacity to adapt that is built into all of us. How they function with disability becomes normal (for them), assuming access to the resources and tools needed.
Make It a Collaboration
Some people don't like to accept help because the helper/helpee relationship can feel belittling, even infantalizing. If you are coming from an attitude of, "Your life is difficult so I want to make it easier," then you are likely to behave in a way that feels patronizing. Think instead of a collaboration of equals, in which you each do your part. From their expertise they will guide you in what you can do that they can't. If they don't yet have mastery, then the two of you will problem solve together so they can gain that expertise in the context of respectful partnership.
Their Safety Comes First
When trying to help — however sincerely — you could actually put someone at risk. Proper help can require some expertise on your part. A blind person, for instance, can be unstable on their feet, so just taking their arm can throw them off balance. A wheelchair user is highly sensitive to the terrain so they won't be thrown from their seat; someone pushing them must understand this. Imposing yourself to "help" without asking first can literally endanger someone. This is probably the most critical reason you must accept their answer and their guidance.
Steve, IT Professional, Paraplegia
The above videos are from Gary Karp's computer-based disability awareness/etiquette course, "Real People. Real Potential."
Learn more at www.RealPeopleRealPotential.com.
Copyright 2015, Gary Karp/Modern Disability
H'Sien, Ph.D. Research Psychologist, Paraplegia