Notebooks - sh.itjust.works

I’m looking for notebooks that I can have with me pretty much always. I’ve had a few TBIs and my memory is all kinds of messed up. I’m looking for notebooks that I can use to easily catalog notes, and solutions to problems and such. I need them to be tough because I do a lot of outdoor stuff for fun and for work. I work on cars for fun, I go hiking, and kayaking, and I work with petroleum and the environment and so on. I guess I need them to be a decent size but not too big, because I think I’ll have to carry a few to separate work from hobbies, from day to day stuff. Any ideas?