In setting your goals, try to be objective. Be reasonable but challenge yourself as well. Keep the fun in everything you do if it's at all possible, and where it's not fun try to see quirks and foibles that make it a bit lighter. Even in the most solemn of endeavours there are moments of encouragement and accomplishment that make it all worthwhile.
I find that most of my goals are very easily met, but that the challenge is setting the timeline appropriately. This is true of destination trips I have in my sights, as well as renovation projects that need to be done, upgrades of things around the house, and, longer term, retirement strategies.
So when I see people who have just started running, for example, I know that there are many things that they have to discover on their own in the course of time, even if they read everything there is to know beforehand. People progress at different speeds. When I ran a 10km race three years ago in 53 minutes, I thought there was little chance I would ever run as fast as my buddy who nailed that race in 49 minutes. Well, I hit the 49 minute mark this year in the Terry Fox Run, so it went to prove that anything can happen if you persist.
So don't be discouraged by setbacks or injuries. Keep at it; you'll be amazed at what you can achieve. Happy trails in 2011!