There are weeks when I look at my To Do list and just giggle hysterically, knowing there's no way I can get through it all. The urge is strong to just give up and not bother. If I gave up some things, life would be so much easier. SO much easier.

     But there's a kind of sheer bloodymindedness that comes into play. Both for martial arts and for writing. Neither of them are easy. Both will deal painful injuries to either body or heart.

     So why do we do it?

   Biologically, it's because humans are addicted to the endorphins our brain releases as a little reward for achieving goals. That little glow of pleasure when you type The End. That thrill when you finish your grading and get handed your next belt. That's your brain rewarding you for hard work.
It's a neat feedback loop evolution has given us to keep us motivated for survival. 

   Which is why reminding someone of that potential pleasure can be such a strong motivator for them to keep going when times are tough.

   When we do our hajime classes in aikido, the first one is hard because you don't know what's coming. Two+ hours non-stop of gruelling training at top speed and full effort. Two hours of being punched, thrown, pummelled, and thrown again - over and over without ANY breaks at all.
     Sometimes the only thing that keeps you going is the fear of looking weak before your sensei and your training partners. Or the sheer bloodymindedness I mentioned before. The "I will NOT let this beat me" type of thinking.
    The second one is even harder because you DO know what's coming. And you choose to push yourself to the limit again. To persevere when others quit or don't even start. To not give up because you want to be proud of yourself and you love that rush of self-pride and confidence you get at the end. Knowing you've done something really difficult.

   It's similar in writing. Often the first book or story is difficult, but we don't really know enough to understand how hard it could be. So we plough through, grit out teeth and struggle through to the end out of sheer bloodymindedness. 
    Then we're faced with the second book. Often now accompanied by terrible doubt because we've now realised how much we didn't know last time. And we're aware that people are waiting to see if we can pull off another good book, or if this one will suffer from badsequelitis. 
    So the trick is to remember the rush. Remember how great it felt to type The End. How excited you were when your first good beta-reader feedback came in and you worked out how to make the story even better. How ecstatic you were with your first good review. 
    Forget all the doubts and fears that you won't make it. You will. Whether it's your first or your second or your twelfth book. The rewards are there at the end. Persevere. Push through the pain and doubt and exhaustion.
    It's worth it to share your vision with the world. Even if you change only one person's life a little bit. Even if ALL it does is make you proud of yourself. It's worth the effort. 

  This has been one of those 'why the heck am I doing this weeks'. You know what I mean. When you doubt you can write, you doubt anyone gives a crap about what you write, you doubt whether it's all 'worth it', you wonder if you'll ever feel like a successful author (hint: probably not).
    Those moments are really about commitment. How committed are you, really, to achieving whatever goal you set yourself?
In martial arts training, a lack of commitment by the uke (partner) causes problems for the nage (person performing the technique). And visa versa. Most injuries happen when uke doesn't attack hard, or because nage doesn't throw with full intent.
    Sometimes nage panics and lets go too early in the throw, preventing uke from learning to fall correctly. Or uke lets go (or doesn't jump properly) out of fear of being injured, preventing nage from learning how to do the technique properly.
    And, in an actual attack, if the victim doesn't commit fully to fighting back - with the awareness they will have to both take and give damage until they win - they will most certainly lose.
    In writing, once you've decided you want to write that novel / get that publishing deal / get short stories into professionally paid magazines / etc, then it will take commitment to achieve that goal. You can't half-arse it and expect to reach your target.
    You have to start the novel AND finish it. Then get feedback AND apply it. Then get editors - AND develop a thick skin and accept your writing isn't perfect the first time (taking damage to your ego, possibly). Then spend the time finding agents or publishers or learning how to self-publish AND handle rejections and bad reviews you might get.
    At any step, you can quit, of course. 
    But if you really want to achieve your writing goals, you have to accept that you will take a certain amount of mental and emotional damage along the way. And you have to commit to the process of getting better at everything, following all the steps, and hanging on for dear life until you reach your goal.
  If you're going to jump into this hobby / career, then jump wholeheartedly, with full commitment to being the best you can in order to achieve whatever goal you've set yourself.