Look at my progress on my #100till1yr goal! I only have 2 miles left and 2 days to do it in. I knew I could do it. It was a great way to challenge myself to get out there an move even if it was walking laps or walking a round of golf. It counts! I actually found out a co-worker does something similar, she tries to get 100 miles in every month and keeps track.
Try something similar, if 100 in a month is too much to start with (over 3 miles per day) try 50 miles to start. It gives you something to reach for.