[Bob Smith]

Other than Grizzly, I think most people dont know what they are talking about.

First, 4 miles A WEEK of running isnt going to have any effect on gaining weight. Thats about 200 calories a week, big freaking deal. Stacey, keep running if you enjoy it.

Second, you need to lift heavier. Grizz is right, lifting 20 pounds for 100 reps isnt going to get you the results you want. Rather, it will get you the results you already have.

Third, you wont gain muscle if you eat like a bird. Up your calories about 500 per day to start.

For a good workout, you would make awesome progress on a 5x5 program. I would bet youre not quite to the point of being able to handle that, so 3x5 (3 sets of 5 reps) would be a good start. You want to work with a weight that is heavy, where if you really pushed it you could hit 6, maybe 7 reps in that set, but stop at 5. A basic program might look like this:

Squat 3x5
Row 3x5
Incline bench 3x5

Repeat on Monday, Wednesday, and Friday for 6-8 weeks and you will notice huge changes in your body.