carrying/using expressed breastmilk question

how am I supposed to carry around expressed breastmilk?

like do I keep it cold somehow or whatever temperature my environment is?

I'm clueless!

They sell diaper bags with insert for a bottle and frozen pack, like a lunch box. That's what I used and you just have to use it cold unless you're somewhere you're able to warm it up. DD2 never has a problem drinking cold breast milk, lol.

Freshly expressed milk
Warm room80-90°F / 27-32°C3-4 hours
Room temperature61-79°F / 16-26°C4-8 hours
(ideal: 3-4 hours)
Insulated cooler / ice packs59°F / 15°C24 hours
Refrigerated Milk (Store at back, away from door)
Refrigerator (fresh milk)32-39°F / 0-4°C3-8 days
(ideal: 72 hrs)
Refrigerator (thawed milk)32-39°F / 0-4°C24 hours
Frozen Milk (Do not refreeze! Store at back, away from door/sides)
Freezer compartment inside refrigerator (older-style)Varies2 weeks
Self-contained freezer unit of a refrigerator/freezer<39°F / <4°C6 months
Separate deep freeze0°F / -18°C12 months
(ideal: 6 months)

Our fridge always got super cold so I'd just pull it out of the fridge and by the time he was ready to drink it was still pretty cold. I have a diaper bag now that has a bottle holder that keeps them cold and don't need ice packs. If say it would depend on how long it would be before needing it.