Running/walking during pregnancy

I'm very overweight, almost 215 and 5 2, in my second trimester, I've been walking about a mile maybe 2-3 times a week, but I'd like to be walking 3 miles a day, every day, is this possible/safe? I'd like to do some light jogging during that time as well, I've also been doing yoga and core training for pregnant women on YouTube, a total of about 30 minutes a day. I want to have a non-medicated birth and I know that working out is supposed to make it easier, Prior to being pregnant I never worked out I'm just wondering if it's safe to start. I'll talk to my midwife as well but I'd like to see what other people's doctors tell them as well.