How do you keep drinks/food cold while out?

I put those blue ice packs from the grocery store in my soft-sided lunch cooler every day, keeps the drinks and sandwich cold. I have two of them in the freezer, great thing is they don't melt and make a mess. Frozen water bottles are great too, take less room than the extra blue packs.

 

the frozen bottles work well, this past Friday morning I had one of those larger 2 gal water jugs and a 2 liter bottle frozen I put into my ice chest (large 60qt) and a couple inches of water in the bottom and 4.5 days later the ice finally melted but the water is still ice cold and I was almost able to go my full 5 day work schedule without needing to buy ice, this next week I might just do 2 of the large jugs and maybe will make the whole 5 days this time.