Its also hard to add much muscle running. Most runners have a very lean look, especially in their legs.
Hello Kitty is right about the diet and the cardio. Whether outside or inside mix it up a little. Maybe do HIIT 2 times a week and other kinds of runs like tempo or threshold the other days of the week. An example amongst a thousand variations could be:
Monday: Tempo run: after some light stretching do a pace that is comfortable for you that you could run on for a long time. Hang at that pace for 40 min.
Tuesday: HIIT: After a 5-10 min jog warm up alternate one minute of all out sprint followed by one minute at your tempo run pace. Do this for 15 minutes to start and cool down the same amount as you warmed up.
Wednesday: 30 Min threshold run. Threshold is a place where you are running between that tempo run pace and an all out sprint. Its the place thats very challenging and almost putting you over the edge but you can still keep it together. It might take some practice to find how this feels.
Thursday: Same Tempo run as Monday
Friday: Same HIIT as Tuesday
This is totally rough and you could manipulate the days and paces as it works for you. I do all my training entirely on the treadmill and it works for me. I also like it because you know your paces right on and have a way to measure improvement. Saves on skin cancer too
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