Anybody who knows me well has often heard me utter the phrase "do one uncomfortable thing every day." It is paramount to having a groundupSALES mindset. Our success, achievement, and growth all stem from uncomfortable actions. I've comprised a short list below of common uncomfortable actions that sales people and entrepreneurs NEED to do comfortably.

Cold calling - the godfather action of sales - get to use to NO!
Asking the tough questions. The ones you know you have to ask but are side stepping around - be confident and direct - don't let them linger, it only gets harder.
Learn from top performers in your industry if it works for them its not guaranteed to work for you BUT it's working for them for a reason. Be humble enough to model success.
Lose like a winner - smile in the face of defeat because everyone loves a winner. Perception is reality therefore it's important to project a "winning all the time" mindset.
Ask for help when you need it. You're not in it alone as much as you feel like you are at times.

If you can't do these five uncomfortable actions with honesty, passion, and conviction then your playing the sales game at a severe disadvantage. The cold hard truth is tough to hear at times but you NEED to get comfortable with these actions.