After just 12 sessions with the C25K program, I now have calf muscles that I can see the definition of! Just three weeks ago, my calves were floppy, I could swing them from side to side, and now they are toned muscle that doesn't jiggle! Now, if only my thighs had such fast results! LOL I am pretty surprised by the dramatic change in such a short period of time.
Ugh, yes, my thighs are the very last to catch on! LOL! I've had some massive calves since high school marching band and boy were they unsightly with extra fat around all that muscle. Now there's very little fat left and just a nice firm muscle. Love it! I blame running and spinning.
The thighs will catch on too, but for that I think you need other activities like squats, lunges, wall sits and I think spinning has really helped me.