One of the most challenging things to do when writing lyrics for a song is conveying feeling through your words. Being successful at this task can enable you to create extremely meaningful songs with great potential.
To give you a personal example, I just recently had the opportunity to collaborate on a song that was slated to be used for a national TV ad campaign for a high profile electronics corporation.

Every musician knows that practicing your instrument is a crucial part of any professional career. But most musicians have no clue about what it takes to prepare their bodies for a tour or a performance on stage.

You can have all the ability in the world with your instrument but if you've got no stamina physically to perform each and every night, no one will ever know how talented you are.

So one of my best collaborative brethren out in NYC asks if I would be a guest vocalist on his new album...  Awesome!!  Absolutley man!  What do you need?  "Well", he says, "I really don't have any lyrics but I'd like to give you a chance to come up with something if you like."  Seriously?!  Again awesome!  Having artistic license  on what I am singing is a huge advantage for a number of reasons.