I Can't Do This by Myself

The Hero has accepted (or even jumped at) The Call, and is ready to embark upon his grand journey to defeat the Big Bad. Unfortunately, in his excitement, he's left his old friends in the dust. Even more unfortunately, he's just discovered that he has Feet of Clay or that his powers are fueled by The Power of Friendship.

Feeling greatly humiliated and apologetic, he must now convince his friends to rejoin him in the fight. A simple apology won't cut it after the way he brushed them off. They're not coming back until he says "I Can't Do This By Myself"; only then will they rejoin him, and even then they often feign reluctance to drive the point home.

This is also said when an otherwise independent person tries to recruit people. The independent people are embarrassed to admit that they're unable to answer the call by themselves. They don't have the added guilt of having abandoned their friends because, well, they don't have friends—they've taken too much care in avoiding friendships before this. The person they'll be asking help from will be an acquaintance, a coworker, or, for maximum Emotional Torque, The Rival.

Seen It a Million Times.

Anime
"Luffy: I don't know how to use a sword, Shark Face!!! I don't know how to navigate either!!! I can't cook!! And I can't tell lies!! Usopp: Hey. Luffy: I know I can't live without help from a lot of people!!! Arlong: Shah ha ha ha ha ha ha... what a clever boy you are to admit your own helplessness!!! What a burden it must be for your crew to have such an idiot for a captain. I don't know why they fought so desperately to save you. You lack the slightest shred of dignity or ability! What gives you the right to be the captain of a ship!!? Just what can you do!!? Luffy: I can beat you."
 * In End of Eva, Shinji says this to Asuka when the burden of creating a new world falls on his shoulders.
 * Monkey D. Luffy gets an entire speech dedicated to the fact he can't survive without his True Companions. A recent arc also had Luffy alone making several off-hand comments wishing his crew was present to do what he could not.


 * Played with during the Doom Tree arc of Sailor Moon when Usagi attempts to fight on her own, and even after that neglects to clue Mamoru in. The Sailor Scouts aren't best pleased.

Music

 * Foo Fighters' "Learn to Fly", between second and third chorus: "Fly along with me, I can't quite make it alone..."
 * Red Hot Chili Peppers' "Snow ((Hey Oh))", first verse: "When I sit alone, come get a little lone, but I need more than myself this time..."
 * Red's "Pieces". "I tried so hard/Thought I could do this on my own/I've lost so much along the way..."
 * U2's "Sometimes You Can't Make It On Your Own".
 * "Superman" by Lazlo Bane is best known for being the title music from Scrubs, which specifically uses the lyrical hook of "I can't do this all on my own 'cause I know I'm no Superman."

Machinima

 * In Red vs. Blue: Reconstruction, Agent Washington repeatedly uses this phrase or some variant of it to convince the Red and Blue teams to join his fight against the Meta. None of them would consider Wash a "friend", though - they only join him because they each hope to get something for themselves out of the deal (except for Caboose, who always seems happy to help anyone - even if they don't want him to). In fact, Wash tries everything from pulling rank to outright bribery (though notably not asking nicely) to get the teams to cooperate.
 * Tex also invokes this trope when she realizes she needs one of the "idiots" to carry a bomb for her, as she doesn't have the upper body strength needed.

Video Games

 * Inverted by sci-fi action game Iji - After Dan and Iji's family is killed by an alien invasion, Dan urges his sister to forget about family bonds and throw away her feelings so she can focus on the mission, but in the end, it is Iji's love for her brother and her memories of her dead sister that sustain her through her fight against the invasion. Dan realizes this later in the game and acknowledges that neither of them can do it by themselves.
 * After the 5th case in Phoenix Wright: Ace Attorney, the player is called upon to show the prosecutor Edgeworth a piece of evidence from the case that neither he nor Phoenix Wright could have put together without the other's help. More of an "I couldn't do this by myself", but still...
 * If you're enough of a jerk in Dragon Age, Alistair will call you out for what you're doing to the reputation of the Grey Wardens. But he still remains in your party, adding that he can't stop the Blight by himself.
 * Mass Effect 2 has Shepard saying this to the Illusive Man when told that s/he needs to stop the Collectors and that humanity is at war. Shepard replies "If this is a war, I'll need an army. Or a really good team."

Web Comics

 * In The Inexplicable Adventures of Bob, Galatea tries to get her sister Molly to help, because she doesn't want to have to conquer the world all by herself.