In a job with rather random hours and a lot of working away from home it's hard to hold down a gym membership. Most gyms charge a monthly rate for access or a much higher price for individual sessions (to encourage you to take the monthly option).
I've given up on the monthly system at my local gym. It really isn't geared up for people who work away from time to time. I used to go three times a week to do a general workout and use their pleasingly powerful showers.
To be honest though, if you do manual work for a living you don't really need to go to the gym.
Not unless you're a bit of a muscle queen.