When going for a ramble or a more serious walk I tend to carry the same things in my rucksack.
I’ve always used ‘mental systems’ so that I remember things. For the great outdoors it’s:
Pasties, sandwiches, fruit, nuts, chocolate.
Plain water to make a brew with the Jetboil and some diluted squash. Occasionally a bottle of beer for summit celebrations!
Thermal smock, waterproof, hat (baseball and woollen cap), gloves.
iPhone. Very occasionally Motorola Radios if there’s more than just me.
Map, compass, GPS (Satmap Active 10 and mapping app on iPhone). Route card. Occasionally guide book.
Petzl head torch, Leatherman, whistle, lighter (Zippo).
CCS camera bag or Lowe Pro depending if more than one lens is taken. Camera, spare batteries and CF Cards. Cleaning cloth and blower brush. Remote release. Tripod (Benbo Trekker or Manfrotto).
I’ve just ordered a new rucksack…a black version of the Berghaus Ridgeway…I’ll keep you informed…