Interval training can start at any level. The idea is that you really push yourself during the intense intervals which you shouldn’t be able to sustain for more than about 30 seconds at a time. During the recovery periods, drop to a pace that would allow you to have a conversation.
While Dr. Budoff finds high-intensity training effective and a good way to vary routines, he advised consulting a doctor before starting, particularly if you're unsure of your heart's health.
Really, really hating running isn’t the end of the world
Good news! The minimum amount of running you need to stay healthy might just be… none. Dr. Hussain said that while the Copenhagen study looked at runners specifically, it wouldn't be too much of a stretch to extrapolate to other activities.
So if you don't want to run, don't. Bike, swim, skateboard -- just get your heart rate up, for at least 20 minutes on average each day. If you stick to that 20-minute rule, you should be (relatively) fine, and don’t feel guilty if you’re not banging out 10-milers a few times each week.