How necessary is it......for what? That question is without a base because I do not know your personal fitness goals. However, if you read the blue print Mark talks about it in there as a key ingredient in this lifestyle. Well, I believe he says to "lift heavy things" at least every so often. Anyway, if your goal is to lose weight/body fat as it is with me and most people on here then its pretty important to that goal. You cant build a strong body with a decent amount of muscle mass without lifting/exercise. And you wont "kick in" your hormonal pathways that respond to excercise by not excercising.Im talking about human growth hormone...the most important of them all for building & maintaining muscle mass.
Anyway, did you read the blueprint? If not, I suggest you do that ASAP before getting into any of this lifestyle further. You seem to be hanging on to some conventional wisdom (CW) hang ups regarding excercise. And until you dispell them in your mind....you cant truly embrace living primal.
If you can just get your....mind together....then come on across to me.....
James Marshall (Jimi)Hendrix