Focus on how your condition affects the PIP activities, rather than relying only on your diagnosis, and explain what you can do safely, repeatedly, to an acceptable standard and within a reasonable time. Give specific examples of difficult days, how often problems occur, what help or aids you need, and the impact on your daily life and mobility; a diary and relevant medical evidence may help. Be honest and consistent on the form and at any assessment, and keep copies of everything you submit. Check the latest guidance on GOV.UK, and if your claim is refused, consider asking for a mandatory reconsideration within the time limit.