A while ago, my husband bought me a CamelBak. This is really super useful – I tend to get a bit panicky if I haven’t got anything to drink when I’m running but carrying a water bottle often gives me sore hands. I blame sitting actuarial exams throughout my twenties – it’s given me arthritic fingers.
There isn’t a huge amount of space to carry stuff but it will take my phone, keys and a credit card or some folded notes. I can even take it skiing (although the water tube sometimes freezes).