How can you become better physically, mentally and emotionally?
A general rule could be to do things that challenge you and not in the scope of your current skills. You have to train and practice in the aspects that you are currently weak. You have to try to make progress on the things that are not in the realm of your current abilities and capabilities.
To become stronger physically, you need to attempt on doing something that challenges your current physical strength like trying to lift a heavier weight than what you could lift comfortably. In order to have better emotional strength, you need to either do activities that support your emotional health like meditation, deep breathing techniques or yoga or even read books.
In order to adopt and grow in any area of your life, you need to strive to force yourself to do uncomfortable and suffer for a while that helps you reach higher standards.
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