"Mastering your life, instead of exhausting ourselves by sitting in front of the stumbling block and sighing in despair."
^ This sentence sounds like a fragment or incomplete in thought. Mastering your life what? What happens then? Is this a command, is this a statement? What is the purpose of saying this? There needs to be a follow-up to it. Statements with commas that do not elaborate on the first part are not good sentences. A bad example is: "Eating healthy food, instead of eating junk and getting no nutrition." Eating healthy food what? Again, what's the purpose of stating this? It seems that there is no point to this sentence because it does not say anything of substance. A good sentence would be: "Eating healthy food, instead of eating junk and getting no nutrition from it, is a much better choice for your body." This sentence states that doing this has a result of some sort. But the sentence you wrote has no result, making it void of meaning.
"Only a conscientious summary of setback can make you comprehend the delight of life; and you can achieve success after overcoming frustrations."
^ You have to either say "a setback" or "setbacks." Hanging words without articles are not good unless mentioned in plural because the word is a common noun and not a proper noun (not a name).
^ Do you mean "the delights" of life? It would be beneficial to say it in plural form rather than in singular because life has more than one delight.
Hope this helps.