Perhaps, these reasons go without saying...and writing...and reading. If you already have this topic covered then please check out How to Kill a Good Idea.

For those who want help...

10 Reasons Why You Should Not Volunteer for Difficult Tasks

10. Difficult tasks, all else being equal, take more Time...time is a precious commodity!

9. Difficult tasks, all else being equal, involve more Work...that drains your energy....no reason to drain a limited commodity.

8. Difficult tasks often create exposure to New Things...New Things can be real scary.

7. Difficult tasks lead to Innovations; innovations generally mean more work...you might knock over a string of work-dominoes. 

6. Sooner or later, someone else will volunteer. When that happens you can take on the important role of Devil's Advocate.

5. That's not part of your job. Develop the habit of stating "Not my Job!" promptly and with confidence as soon as you catch wind of a difficult task. That way, other folks will learn to respect the boundaries of your role. [PS - of course, persistence is required here if the other person is your boss.]

4. You will lose the opportunity to talk behind people's backs. Certainly, you don't want to risk falling off the gossip grapevine.

3. You will deny yourself the pleasure of watching other people struggle, especially folks who are a lot less skilled or experienced than you. Some of those folks put on a terrific performance. [Side benefit: you get to watch dramas unfold at work...it's like getting free movies.]

2. You will remove your ability to say, "I told you so...I told you that wouldn't work!" if/when other folks fail at the difficult task...as they most certainly will do from time to time.

1. Difficult tasks can be dangerous! If you ever start to lose sight of that, think about Tightrope Walkers. It is thrilling to watch them...but have you ever known anyone who volunteered to be one?