How running helps me overcome self doubt

I have been really struggling with self doubt lately.  Badly.  I took on a new goal and things that I've thought daily include:  "What the hell was I thinking?"  "Why did I think I could do this?"  "Why am I doing this to myself?"  "What if this doesn't work?"  "I'm going to have to buy new pants!"  

This has gone on for weeks.  I've put in the daily work towards my goal but all the while my head has been contradicting my actions.  This weekend it hit me that I had these exact same thoughts when I started running.  "Why would I think it is a good idea to sign up for a 5k?"  "How on earth can I run 3.1 miles if I can't even run 1 mile?"  "Who thinks running is fun, it isn't fun!?"  "What if I'm not good enough?"  

Since my first 5k I've finished dozens of other 5ks and 4 half marathons.  I didn't go out there to win the race.  I just went out there to prove to myself I could do it.  Ever since then I've been competing with myself to get better.  And I've had thoughts about whether or not I could improve on my times but never have I doubted if I could finish a race.  Self doubt doesn't plague me like it did before that first 5k.  Not to mention, running became fun!  

So after this brilliant insight hit me this weekend I realized this new goal of mine is just like signing up for my first 5k.  I was/am scared of what it takes to get there and it is overwhelming, however,  I know I can achieve my goals so why let self doubt waste my time.  

I'm re-reading the book Relentless by Tim Grover.  He has so many motivating gems in it that I grabbed a notebook and started making notes so I can refer to it when doubt starts to creep in.  A few of my favorite things Tim points out:

-Patience is the hardest part of any goal.

-If we're talking about being elite, if you want to be unstoppable, you have to learn to put aside everything you've been taught, all the restrictions and limitations, the negativity and doubt.  You have to stop thinking.  

-There's a certain fulfillment that comes from testing your own limits instead of stopping where others claim you are capable of reaching.

-Never let others standards define your own.  

-You have to play the last game of the season with the same intensity as you played the first.  

I think I have mentioned this book before but if you like no BS motivation this book is full of it (no pun intended?).  I  have this book so highlighted and underlined it is like a textbook.

So overall what I learned-I let myself feel the doubts, think about them and then realized I have had doubts like these before and running showed me I can conquer them and do hard things.  One of my running mantras is actually "I can do hard things."  When I start to face doubts during an actual run it reminds me I've done harder things than what I'm doing in that moment.  Whether in life or running up a hill so long and steep I'm cursing my decision to sign up for that run and questioning again who runs for fun, the doubts go out as fast as they come in.  So new goal, same doubts, and I know it'll be the same outcome.  I can do hard things.