How can i prepare mentally and physically to work 7 days a week(for about a year)?

Physically, you need to take good basic care of your body. A good night's sleep is very important. So is good nutrition. You can't function properly at your job if you stay up too late or live on junk food. Keep a supply of healthy food such as fruit, nuts and granola bars handy for a quick meal on the go.

Mentally, you need to keep your eye on the goal. Since the 7 day shift is for only one year, you can create a count-down calendar. If the reason for the extra work is to earn money for a specific purpose, keep reminding yourself that each day you are closer to that goal.

Accept that you will miss some events, but try to think long term. Two or three years from now will you still be upset about missing the event or will you be glad that you were able to stick to the 7-day a week schedule to accomplish your goal. Plan small treats for yourself if your schedule starts to get to you. It could be a night out (not too late!), playing computer games or a visit to an old friend--anything that lifts up your spirits.

As far as the physical side, it would depend on the rigors of the position you'll be working...not much prep if it's a sit-down job.

However, you mentally can prep...just think, if you decided to become a parent for the first time, you're going through the same type of adjustment. You'd be on call 24/7, sleep would be interrupted for months, and you eat/rest/socialize when you have the time. You would adjust to the new lifestyle.

Normally when there's a 7 day a week job, you'll be pretty much on task all the time, so you'll learn to think professionally, and break into "relax time" just long enough to regroup.