In this article we propose a novel approach for mobility analysis by isochrone overlapping to aid urban planners in the decision-making processes of walkable cities for all citizens. This approach focuses on the pedestrian mobility of older citizens but can accommodate different accessibility requirements to quantify the mobility of users. As will be seen, the proposed approach offers great insight for the X-minute city concept and chronourbanism as it unveils new data exploitation that enhances spatially aware analysis and optimization. The reduction in computation complexity of simulation has been quantified and tested. A streamlined workflow is proposed for the evaluation of indicators related to accessible walking and also the identification of the best locations for new services.