Hip pain.

So I'm back at the gym. And for the longest time, way before I ever got serious about losing weight, I would go to the gym and "work out". Except, I never had a goal. I never had a plan. Now, after losing a bunch of weight, I'm on a mission to keep it off and maintain my loss. Plus, I still have that pesky little 20 lbs to lose.
The sun came out last week, and I felt alive again. Three days at the gym last week, and after I finish today, that will be another 3 days this week. I think I would have gone 4 days, but things came up, and I had to skip Wednesday.
In the past, I've not pushed myself much. But now, when I get on the treadmill, I visualize myself with long, lean legs. I really want to lengthen my muscles, and get those great legs back I used to have. Well, I thought they were great. And compared to what they look like now, those legs I had in my 20's were great!
So I get to the gym with a plan to walk/jog 30 minutes to an hour, and I usually do about 40 minutes before my tendonitis acts up.
On the inside of my right hip, along my pelvic bone there, I have some tendonitis. I can set the treadmill for 4.0 - 4.5, and I'm fine for awhile. It's when I set it higher, around 5.0 - 5.5 when I get into trouble. As that tendon heats up, the pain goes up. If I keep my pace right around 4 mph, I can go longer, but my goal is to get down to a 12 minute mile. I'm trying, but that pain is slowing me down. I can only tolerate so much, before I have to lower the speed, and let my hip cool off.
Here I had been worrying about my back causing me to go slower, or cut back on the walking. But so far, my back has been very nice about this jump back into exercise. It's my old lady joints that are fighting back.