Once you've worked out how much you need, then you've got a figure you can save towards. Some people make this number their screensaver or put it on their fridge using this saving goal as motivation to go to work everyday.
Have your very own telethon-style countdown as you save towards the goal. If you find saving tough, try budgeting software like Pear Budget or Mint – the latter includes countdown functions for your savings and can suggest ways to cut your expenses. If you don't hit your saving goal, then it might be time to go back and re-visit the budget - maybe that Singapore Sling might have to be in a more down-market bar.