This is a great smoothie for breakfast or pre and post workout. You've oats for sustained (or replacing) energy and the milk / yoghurt to provide protein to help and speed muscle recovery. Also the berries provide fibre and a load of micronutrients (vits and minerals).
125ml milk of your choice
125ml low fat greek yoghurt
125g frozen berries (use a mix if you can of blueberries, raspberries, blackberries, blackcurrants etc)
A tsp of honey
Blend well until smooth!