For lunches I really like the small tins of flavoured tuna, like these Clover Leaf ones (I really like the spicy thai chili). I've paired these either with a bagel or some crackers (you can also buy the snack kits that come with crackers, but they aren't quite enough for an actual meal on their own when outdoors).
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Victory awaits him who has everything in order — luck, people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck. Roald Amundsen