I'm SAHM with my 2 year old and it is the best thing for him. Most of the time I love it, but am going through a mind-numbingly bored patch right now. DS used to need me so much, I couldn't get anything done. Now he wants me to hang around while he plays independently and what I should be doing is the dishes, tidying, cleaning etc. but I didn't take time off work to be a housewife so I really resent feeling guilty about household chores. I think I need another baby.....
What keeps me sane most of the time is activities - I have something structured to do every day except Fridays, and I find it really helps to have a routine of activities so you're not constantly thinking "What can I do today?" It's more, it's Tuesday, so it's soft play day etc.
Good music classes are good for the mummy brain drain as you get to learn all sorts of new songs and the ones I go to the learning curve is actually quite a challenge - 3 repetitions and you're expected to be word and tune perfect LOL. I'm also doing bits and bobs of Open University, supposedly on some committees for church and charity, but sometimes I find these dispiriting because I'm not doing them properly.
Sometimes try to make myself recite DS's books from memory, to keep brain alive and it means I always have story at the bus stop. Am thinking of trying to learn the art of storytelling, as I think it would be a fab thing to do and quite a challenge for me. I also try and play the oboe and DS doesn't mind me honking along to a piece of music for 20 mins or so once in a blue moon.
Find it hardest when I'm trying to give DS a peaceful day. He'd love to stay in 24/7 and play with his toys, but I go bonkers after half a day and have to get out.
Inviting and visiting other mummy friends is great too, but beware you don't get someone latching onto you who is using your house as a place for toddlers to trash AND you have to make tedious conversation with her too. Sad to have to write this as all my friends are lovely bar one who is very persistent and quite shameless about inviting herself round.