1- You'll be in contact with nature: either for those who're nature lover or those who aren't, to be in contact with mother nature is always good for the spirit, the inner peace, health, stress and inspiration.
2- You'll be able to look into you: sometimes the busy routine, the loudy streets and all the characteristics of cities don't allow us to take a break of all these "exterior" things and take a look to ourselves -our needs, our mood, our health-. The silence you'll find will allow you to think more fluently, the phisical work will help to quit the sedentarism and generate some endorphines -hapiness hormons- and the free time you'll have -since you'll be far away from your responsabilities, known people, own house- will open you the door of creativity for new projects.
3- You'll apreciate much more all you have -in the city and in life in general-: By learning how difficult is to have warm water, how complicated is to grow things and process them; you'll be more concious about sustainability, global envoirnment and more. I personally belive that if humans learned what how difficult is to produce food -and how it should be done- or to get some comodities -as warm water or materials-, there'd be a natural global apreciation for food and materials, a sustainable-conscious society, and probably no problems with eating too much meat -because getting to know the animals and how difficult is taking care of them would, either made people fall inlove with them and stop eating them, or at least eat less amount because all the work and time it needs to be raised-.
4. You'll learn about traditions -from your country or the ones you visit-: The countryside is where normally most of the traditional things remain, as it's more difficult that it recives "external-changes" as quick as the main cities. That's why if you go there you'll quickly discover ancient tricks, recipes, quotes, that define your country -or the one you're visiting- and shouldn't get lost, because they keep the essence of one culture.
5. You'll improve some skills that probably can't in the city: Maybe in the city you don't have time enough to cook -and much less to grow/raise what you eat!- and there you'll get the chance to improve your skills, or learn them from zero. Also with agricultural and carpintery tasks you'll have the chance to learn -or create!- ways of fixing or designing things. The up's and down's of the land, the lacking of public transport or other transport comodities, the field work, will force you to make exercice even without noticing, breathing fresh air and getting tan with the sun.
These are some of the things that I get beneficiate of when being at home -in my farm- or travelling and working at rural areas, but I'm sure you'll find many other ones when you experience it and'll get back home with a happy feeling -from your soul to your body-.
Here you'll find some websites that allow you to do some activities in rural areas or to travel by doing farm work :)