This has been a big hit in our house for years, and is particularly good the morning after the night before!
Put into the blender
1 banana good handfull of berries and/or soft fruit (mango is particularly good, but anything in the fruit bowl that's past it's best is fine) Handful of oats Good dollop of yogurt Top up to 500ml with any juice you have in the fridge.
Blend well and serve.
If you prefer it chilled, use frozen soft fruit straight from the freezer.