Before you leave your house every morning it's a good idea to have a plan for lunch*.  Otherwise it's way too likely that you'll get stranded with very few unsatisfying options.  Here's an algorithm to use:

1. What options will be available? (food you could take from home, options to purchase at lunch time, lunch already provided by your organization, etc)
2. What sounds good from the options available? —> Go with that. 
3. If nothing sounds good, you may just have to pick from what will work as fuel for your body.  Not an excuse to skip lunch.
4. If something else sounds good, is there a way you can get it for lunch?  If so, go for it!  If not, return to step 3. 

*This algorithm could be applied to any meal.