Do you warm up before stretching? I am asking because warming up before stretching makes stretching both safer (by much) and probably more enjoyable, as warm muscles allow a larger range of motion. Swimming also helps with neck pain. Actually, some people who have tension headaches get relief from swimming because the way the body is positioned - spine, then the neck, and then the head with face down - relaxes the muscles in all the right places. You do not need to swim fast - what matters is the form (alignment) and not the velocity. If you get bored, buy a waterproof ipod shuffle on Amazon and listen to music while you swim. This is just a general recommendation - since you mentioned a "regular" headache in OP.