What's in Your Day Bag ?

So I'm about to head out on my first solo trip ever. I'll be spending one month in Thailand! Needless to say I'm both excited and nervous. Can't believe I'll be leaving in 6 days. I think I packed and repacked my bags twenty times over the weekend. This pic is what I plan to carry in my day bag for most days. It ended up weighing unde 7 pounds so should be fine to carry to markets, hikes or the beach. Any pro travellers have and advice on 'must' bring items?