I do a lot of running but I also hit the gym 5 days a week. When I start running I start off slow to get my body used to running again, I don't go all out because I don't want to strain/pull/etc. anything, so getting the body warmed up for a few days will work, for me anyways. At 32 I run a consistent 6 minute mile which includes slight elevations and I weigh 253. I'm going to get my real time this year at the high school track. Not sure if you mentioned your shape, body weight in this thread but over time you should be able to run under 11 minutes. You should also do 100 yards dashes, etc. Learn to pace yourself, do not go all out right at the start, you will be dead halfway around the track. I remember in high school when we had to run the mile, most of the class took off right at the start, around mid-way I was passing them. I had didn't have any challenge so I ran a 5:40 mile, the guy that would have been a challenge was out that day, I could have ran faster or slower, never really got to find out.
You should probably also look at your diet, eating clean will help you a lot, losing weight as well will help. Make challenges for yourself, get on YouTube and look up different styles of running, etc. Use weights around your ankles or in your backpack, run up steep hills, even riding a bike will help. Just get out there and do it