lexica510 points to some research - small sample alas - which suggests that being in nature confers great psychological benefits, and we tend to underestimate how good it will make us feel. It certainly does me a great deal of good.
While I was there we went to Lindisfarne of course, walked the beach near Bamburgh, and visited the Baltic art gallery in Gateshead. I saw the Millenium bridge tipping up to let boats through.
What I would particularly recommend for visitors to that region is to call in at Barter Books in Alnwick (home of Hogwarts). It is one of the largest second hand bookshops in the UK. It is beautiful, calm, fragrant (open fires) and has a wide, but not comprehensive, selection, in a converted station, and there's a good cafe. I ended up feeling I could not justify spending money on beautiful editions of books I already own. The most mouth-watering thing I saw was the complete works of Edgar Allan Poe, in black leather with sparse silver filigree. That was about £450. It is a great place to spend a rainy morning. I just bought a couple of cheap paperbacks of things I wanted to read.
I would like to go back to Northumberland, maybe in the spring, and walk up the coastal path from Newcastle to Berwick, stopping at B&Bs, and I could call in to see my brother.
ETA - Fun Fact! The '"Keep Calm and Carry On' poster was discovered at Barter Books. It had been printed during WW2 for use in case of invasion, which obviously never transpired, and it was then lost and forgotten.