On Committing to Projects

Lately I've been complaining to at last two (2) people that I have a hard time turning down offers to be involved in things and commit to things, because I am afraid that I an amazing opportunity will pass me by and I'll be pissed at myself for not getting involved, and then I get nvolved and am upset that I am not able to devote the time and energy to it that it deserves, and then I'm upset with myself for getting involved. 


One of my friends (Anne) suggested that what I need to do is truly evauluate how the involvement makes me feel, like on a an emotionally physical level. Am I excited to do this task when I get right down to it? Does it physically make me feel good? Am I (god forbid) ENJOYING IT? This seems like such good sense that I should write a book about it. No! Not a book about it! Just you, know, take it to heart.


Another friend of mine, Laurel, agreed that she does the same thing too. She said "I over-commit all the time. I think it's because I get easily excited by new ideas and I'm bad at estimating how much time each will take and how much time I have to devote to these things. I think if I were more honest about my capabilities vs. eagerness, I would be able to dole out time more effectively."


Why does it take other people to point these things out to me?