The low intensity general work like tempo will make you huff and puff and sweat like a pig while you’re doing it, but an hour or two later you’re fine.
In contrast, the high intensity training usually doesn’t feel like you’re working that hard because there isn’t much endurance involved, with some exceptions (i.e. SE). But a couple hours later it will start hitting you. That’s what usually gets most people in trouble. They don’t stop the high intensity work until they start to feel it. Way too late.
So start easy no matter what it is.