( CNN ) -- Only 20 minutes so far ? I ca n't keep sitting on this bike . It hurts . I 'll just leave class and use the restroom . I do n't need to go to the bathroom , but it will give my rear end a break . What if everyone stares at me ? Oh no , now my toes are going numb ! These thoughts flew through my head during my second spin class a few weeks ago . Recently , our Fit Nation workouts have picked up in intensity . I have tried new activities and pushed myself beyond my physical comfort zone . When this journey began , I envisioned the biggest obstacle to my success would be physical . But after seven weeks of training , I have become acutely aware of the body part that needs the most conditioning . And much to my surprise , it 's not my abs , triceps or quads . It 's my mind . I 've come to the conclusion that wanting to stop mid-workout has little to do with my body and everything to do with my mind . I know many folks who experience negative self-talk , where that little voice in your head tells you all the reasons you ca n't do something . My internal dialogue seems to be less focused on telling myself I ca n't do it and more concerned with developing and executing a workout exit strategy . My brain does n't say , `` You ca n't . '' It says , `` You should n't . '' Oh , but I should . And I am . Change your mind , and your body will follow suit . But how do you change your mind ? That 's the million-dollar question . T-shirt tales : The athlete I used to be . It turns out some cliches are true . The first step is admitting you have a problem . Hi , my name is Tabitha , and I can talk myself out of a workout before I start . I had a long day at work . It 's raining . I need to put gas in my car . It 's Monday . Venus is in retrograde . You get the idea . Excuses and justifications are the path of least resistance . Here are some other cliches that have proved true during my training : . Listen to your body , not your head . I 've been in the middle of many workouts when I desperately wanted to stop . But when I focused on what I was doing , I could ask myself , `` Do I want to stop because I am in pain ? Or am I just uncomfortable because I 'm sweating , breathing hard and making my body stronger ? '' If I am honest with myself , the answer every time has been `` I 'm just uncomfortable . '' And guess what ? I have finished every workout I have started . Get fit and others will follow . The only thing we have to fear is fear itself . I recently read the amazing book `` Finding Ultra '' by Rich Roll . In it he writes , `` There 's only one cure for fear . Faith . '' That line resonated with me . It helped me understand that as an adult , fear has prevented me from realizing my full physical potential . In the past , fear is what has stopped me from even trying . So now , if I find myself dragging my heels about a workout , I try to identify the why . Usually , it 's something silly such as fearing the embarrassment of sharing a lap lane and slowing down another swimmer . Now when I go to pool and find myself in this situation , I simply watch the swimmers for a few minutes . I try to identify someone close to my speed and skill level . I then ask if I can share the lane and tell him or her upfront that I am new to training . This has worked every single time . The real key to overcoming these fears , as Roll pointed out , is faith . Have faith in your journey , in the universe and in yourself . Why being part of a team matters . A picture is worth a thousand words . Everyone , even the toughest endurance athletes , occasionally struggle during workouts . Sometimes the only way I get through particularly tough workouts is visualization . At times , it 's remembering the two years I spent in nearly constant pain as I battled ulcerative colitis . Compared with that , the aches and weariness of triathlon training pale . More often , I like to visualize my eventual triathlon success . I envision myself crossing the finish line on a warm , breezy day in Malibu , California , this September . I see myself running into the arms of my husband , daughter , parents and sisters . I imagine that magical mixture of physical exhaustion , elation , pride and disbelief that I actually did it . And it keeps me going . Oh , and that spin class ? I did not stop . I finished the class without stopping . And then I ran for 20 minutes afterward . Follow McMahon on Twitter @ TriHardTabitha .
Wanting to stop mid-workout has little to do with your body , Tabitha McMahon says . McMahon : Train your mind , and your body will follow suit . Triathlete in training visualizes herself crossing the finish line on tough days .