I dig this statement from Gil Penalosa of 8-80 Cities:
"This is where the “8-80” city concept comes in. The 8-80 city is based on the premise that if you build a city that is great for an eight year old and an 80 year old, than you will build a successful city for everyone.
There is a simple exercise we do to help people understand the usefulness of the concept. First, think of a child you really love who is around eight years old. Next, think of an older adult you care about who is about 80 years old. Once you have that child and that older adult in your mind, ask yourself: Would you send them out together for a walk in your city? If you would, the public realm is safe enough. If you wouldn’t, improvements are needed. We need to stop building cities as if everyone was 30 years old and athletic. If communities are great for the eight and 80 year old, then they will be good for all, from zero to over 100."