The phrase "Nothing is impossible" is not literally true, and if one wished to be pedantically philosophical then if "Anything is possible" then one possibility is things can be impossible. There are impossibilities like perpetual motion machines or reversing the law of entropy, for sound, proven, verified fundamental reasons. Although we do have flying machines called airplanes, humans flying in the air through brute physical effort is impossible because it's impossible to cyclically flap your arms fast enough for your body weight. Aside from the fact your examples bear no relation to the topic at hand, psychosocial dominance, the point is "nothing is impossible" is a meaningless phrase without nuanced parametric definitions of the boundaries and limitations of the possible and impossible, even for psychosocial dominance.
And as to the quote, "We're all created equal, some of us just work harder to achieve their goals." That's not quite true. People are born with certain talents, certain domains of specialty, which can possibly exceed the capabilities of anyone without the talent. I would like to see you accurately memorize the first 23,000 digits of the number pi, as accomplished by the autistic savant David Tamet, or memorize every name and phone number in the entire phone book of a large city as Los Angeles, as accomplished by the autistic savant Kim Peek. Effort certainly does play a role in accomplishment successes but we're not created equally. People with certain talents will achieve equally comparable accomplishments with less effort than others, and will far sublimely surpass others when putting the full effort.
Don't cry, crybaby...