Naman,
You are not weak...you are stronger than most because you are facing one of the most frightening experiences...anxiety! We are champions, and we truly find our inner warrior when we go up against our greatest fears!
Here is an idea that I thought might help you. I am going to post some coping skills below (I like the stress-relief site best) for you to try.
I recommend doing these 3x's a day for at least 10 min. I also think that doing them before and after your exercise sessions would be smart...but I will leave it up to you, and what your schedule allows.
Self Help sites with breathing/relaxation exercises instructions
Panic attack relief exercises:
http://www.healthcentral.com/anxiety/c/73076/34334/breathing-lessons/
http://www.healthyplace.com/
http://www.stress-relief-exercises.com/
http://www.ehow.com/video_4405003_breathing-exercises-panic-attacks.html
http://www.psybersquare.com/anxiety/panic_relax_I
Lowering your overall anxiety through these skills/practices...as well as doing your exercise (remember moderate and steady at first) should help to get you back to where you want to be.:)
Best wishes, and keep posting!
S.C.