Ben Levin was the first person to tell me that no matter how shitty you feel about your skills that day, if you look back a year, you will feel great. And it's only when the one year view gets shitty that you need to panic.
It's a good idea, although these days I think maybe quarterly self-measuring (i.e. how much have I improved in 3 months?) might be a lil more of a "fire under the ass" way to look at it