According to Walk in Scotland, the official walking site of Scotland's National Tourism Organization, Scotland was "Created for Walking." Aberdeen is considered to be in the North East walking area, with famlands, mountains, and sea and lots in between:
"Visitors are often surprised to discover that north-east Scotland has a gentle landscape with plenty of easy walking. In Moray and Aberdeenshire the Cairngorm mountains drop to low, rolling hills, which soon give way to undulating farmland. Scenic river valleys dissect the arable and pasture fields, and a good road network links the many towns and villages. Numerous fishing harbours dot the long coastline, which has vast stretches of dune-backed beaches and cliffs punctuated by coves. "
Check out this very healthy 10.5 Kilometer walk entitled "River Don, Beach and Old Aberdeen"