1. Go to the day labor hire sites - (big box hardware stores, Lumber stores, etc) and get triple bonus - every time you hire on a work crew, you will displace one illegal alien, you will get buff, and you will earn $10-15 bux perhour...If you are a good worker, they will look to hire you every day, and you will be rollin in it!!
The good part about this is that you need only work when you want to - the bd part about this is that you might not always get a job when you want to.
2. Do you live near a small Port, one that serves only a few ships a week, and is a long way from a big port? Really good money there - $27.00bux per hour, if you get hired as a casual. Work there till they know you, and they will start letting you drive forklifts, Hustlers (the big semi bobtails used to move containers), and so on...
3. Any big trucking terminals/warehouses/railheads near where you are? They pay $15.00-25.00 per hour. The work is hard, so you will come home tired and sore every day, but you will get really buff.
4. Any moving and storage companies near you? They pay less than warehouses, but otherwise, are like #3
5. Waiting pays well in a good restaurant - lots of walking, must be polite to the customers, and have to work evenings, but pretty good tips in a good place.
6. Construction: Drywall/Framing/Roadwork/Cement work. (Does your state have regulations/certificate requirements for Flaggers? Find out, and get the cert. Good pay, work outdoors, EASY!)
7. Look in your phone books under Handyman - call and ask if they need an eager young, strong helper - you might get lucky.
I did all those jobs (and more) during my early years.