I know it takes time but you can do it !!
Take a Sunday afternoon and cut up everything and place in zipock bags in your fridge. You should have a bag of lettuce, a bag of cut up tomatos, a bag of cut up pepper strips, onions, celery, carrots etc etc.
Buy a good size ziplock container to place your lunch it. Add the lettuce and the cut up veggies .It won't take long , you could even make the salad the night before.
You could also cook some chicken to add to your salad or a can of tuna or a hard boiled egg!