This is one of those hyperbolic statements the fitness industry loves to "inspire" you with.
Suck it up buttercup! This will only make you better!
It's not so much the sentiment that's the problem. Frankly, sometimes we do have to embrace discomfort in order to improve. Growth is uncomfortable. Achievement requires effort and effort ain't easy.
The problem is how we apply this sentiment.
We mistake embracing the suck of the effort to achieve our goals with embracing the suck period. A good life is balanced. We gear up, we do battle with our challenges, we do our best, and then we celebrate with a beer afterwards. Embrace the suck was created to help encourage those of us who'd rather just skip to the beer. It's important to engage with the struggle. There is much to be learned and better people are made from it.
But to be all struggle is just as bad as to have none of it.
To our perfect imperfection,