Ah, the experts talking about drugs again.
Yes, most Mexican and Latino workers post-slavery were smoking a lot of weed while working in order to focus on the work and not eat as much as they'd do otherwise. Hence why "reefer" wasn't a "Negro-drug-problem", but one about stereotypes when it comes to Mexicans/Latinos.
The South Americans (in the north-western part) had a different habit, that is to stimulate their body by chewing on Coka leafs.
As far as weed in the US goes, most of the stuff you get today is Indica Kush (Kush is short for HinduKUSH, the area between Afghanistan/Pakistan and India, where the Indica strains originally come from). Why? Because in the mid-80s, the flowering time went down from 3-4 months (!!!) to after 7-9 weeks and cultivation is simple. Most of the Indica strains have a (initial) head high and then a strong body-high. Hence why you always see the stereotype of fools getting hungry, eating a bag of potatoe chips and then passing out.
Sativa is a different beast. A.) you won't get a good, pure Sativa, unless you pay MUCH MORE than for the Indicas B.) Sativas have a paradox influence on your body; they are anti-depressant, motivational and make you focus on a tasks. Basically an effect not far away from cocaine or even more something like amphetamine. Sativas will make you clear, focused and motivated, unlike Indicas.
Shit, I know of many clinics in Cali which fly in Sativas from Holland and themselves sell Indicas to Dutch coffee-shops.
All in all, if you have physical problems/chronic pain problems, you will probably be better on the Indica side. If you are a grown up, are psychologically stable and can handle a STRONG stimulant and anti-depressant, then you should look for Sativas.
Let me tell you this though; just because you smoke five blunts of that "real, original OG Kush" an hour, doesn't mean shit.
Do the same with 6-7 months (!!!) flowering Lambs Bread and you will scream for mommy and think you are a cartoon character.
And first and foremost. Stop smoking in QUANTITIES. Buy the BEST stuff money can get and ENJOY it. Use it as a stimulant, not as daily "food".