I have been doing modified HIIT workouts all this time, and while the shot to hell metabolism doesn't exactly yield the desired results, my cardiovascular health has improved a lot. Look up fitnessblender on youtube. They have all kinds of free full length workout videos of varying durations (from 5 minutes to 90 minutes) and activity levels . It's a very no-nonsense approach to fitness. And, I am going to be relying on their stuff pretty heavily post DS as well.
Only if it doesn't aggravate your hernia, try kettle bell workouts. There's a good beginner's workout by Jillian Michaels, that I quite liked. Kickboxing, if you're able, may also help.