Going along with the other comments, I think it's about a guy dealing with a rough breakup he went through, probably a while ago. ("So you kissed me / On the futon / Oh I hope you like it in Chicago") The repeated phrases "I won't lose it" and "hold it steady" refer to him trying to hold it together emotionally. He copes by interposing physical strength over his apparent weakness, and declaring this to his former girlfriend. The whole song is framed as a message to her, where he tries to make himself feel bigger and better by declaring the titular feat of strength, and later in a rationalization that there are 'other fish in the sea'. ("Well I met someone who wears your glasses / She kissed me on / My new futon / Oh I'm clumsy cause she finds me attractive") Throughout it all he tries to bolster his self-confidence by repeating to himself "All by myself, I can lift a car up all by myself", when he likely still feels this is a childish justification and he still misses her. I like how the last repeat of the "all by myself" is dropped much lower, it really feels like he's saying with all the pride of a little kid shouting a challenge, but simultaneously feeling a little waver of doubt.
Going along with the other comments, I think it's about a guy dealing with a rough breakup he went through, probably a while ago. ("So you kissed me / On the futon / Oh I hope you like it in Chicago") The repeated phrases "I won't lose it" and "hold it steady" refer to him trying to hold it together emotionally. He copes by interposing physical strength over his apparent weakness, and declaring this to his former girlfriend. The whole song is framed as a message to her, where he tries to make himself feel bigger and better by declaring the titular feat of strength, and later in a rationalization that there are 'other fish in the sea'. ("Well I met someone who wears your glasses / She kissed me on / My new futon / Oh I'm clumsy cause she finds me attractive") Throughout it all he tries to bolster his self-confidence by repeating to himself "All by myself, I can lift a car up all by myself", when he likely still feels this is a childish justification and he still misses her. I like how the last repeat of the "all by myself" is dropped much lower, it really feels like he's saying with all the pride of a little kid shouting a challenge, but simultaneously feeling a little waver of doubt.