I focused on training the muscles I can see in the mirror - it eventually led to postural problems

Hello, this is just a start of my idea that I am going to write for prompt 1 of the Common App. Please note that this essay isn't complete yet. What I have now is really crap.

Do you think my idea is appropriate for the topic? The focus of my essay will be having balance and doing "everything in moderation." So, is my idea sounding like "Jack of all trades, master of none"?

Prompt: Some students have a background or story that is so central to their identity that they believe their application would be incomplete without it. If this sounds like you, then please share your story.

I was the typical guy going for that beach body look. So I focused on training the muscles I can see in the mirror: chest and biceps. I worried I would never have big arms. I decided to start doing dumbbell bicep curls anytime I could - before school, after school, and before going to bed. I also trained my chest from all the angles. This helped. I was making some beginner gains. I was happy with the results and kept working on my chest and biceps. I neglected my back and legs which eventually led to postural problems. My chest was tight and I was having the hunched over look with rounded shoulders.

I went online and looked for solutions to fix my postural issue. I had to stretch my chest frequently to get my posture straight. I read many physiological articles and realized the origin of my problem. I learned that all muscles in my body work as a system. If I am only going to work those "mirror-muscles," those will get big and tight. This led to my posture issues. In order to negate the damages done by those bench-presses and push-ups, I have to work on my back muscles as well. I started focusing on do many pull ups to target my back.

From my experience, I realized that balance is an essential life skill.

From here, I will explain these points:
- having the balance in everything (physically, mentally, spiritually)
- having the right attitude/mindset (to exercise for a functional body rather than look)

While I feel the essay has been well-written, topic 2 (failure, and what you learnt from it) looks a little more appropriate (Just my opinion). And you really need to focus on how central it is to your identity. What makes you unique from the masses? The last line does not fit well as a conclusion, it's a one liner and that is not going to look very neat on your application. Emphasize more on how much the event affected you, and that positive aspects you gained from such a realization.