Need Healthy Lunch Alternative

I'm having big issues with lunches. I work too far from home to go home and eat something, so I'm stuck with taking my lunch in. There are no fridges and there is a microwave. I usually make my lunch the day before, I'm not really creative so all I take are sandwiches. Buying a bag of salad goes bad before the week is out and doesn't fill me up so I usually try it for a while then feel like I'm spending too much money on it. I make my kids lunch for school the night before.

I need something different to bring to work to each for my lunch that's easy to make, can be made the night before and will keep well... I'm hoping with a large peer group like this, someone has been there before and may have a few ideas...

Thanks!!!

Vicki