It's actually really hard to pick my favourites from this album as I kind of love them all for different reasons, but if I have to pick a couple I'll go with 'Overnight' and 'Dot'.
I also want to add a couple of extra songs, so if you're looking for something epic this is a good'un:
If you're looking for something nice:
And if you're looking for something extremely calming:
And if none of these work you can always go for a bit of Beethoven Symphony No.5... now go forth and concentrate!