North Yorkshire lacks only big mountains, this aside it has every conceivable type of walking you can imagine. Ranging from the rolling hills of the Pennines in the west to the north sea coast in the east, within it's boundaries you will find long distance routes, high level horseshoe walks, linear sea-cliff walks, strolls by rivers and through neatly walled fields, bog-hopping epics and marches across limitless moorlands. The problem is not how to find walks, it's which one to choose fro the endless list!
The two national parks are the obvious places to start. If you want summits and big drops then the Yorkshire Dales is the Place to head for. If on the other hand you want wide open spaces then head for the North Yorkshire Moors. Don't ignore the other areas though for there are countless other stunning landscapes to explore. Places like the weird rock formations of Ilkley Moor or the pub linking lanes of the Vale of York.
Covering such a diverse area you won't be stuck for things to do when you don't fancy a walk. York of course is a world class city with a massive selection of cultural and heritage attractions and each of the national parks has its own range of castles, museums. If you fancy expending energy elsewhere then try mountain biking, rock climbing or potholing, some of the UK's premiere venues for each sport can be found here