Not knowing the reason for not selling something. The client doesn’t tell you. Sometimes they give a reason but it’s a “smokescreen” – a legitimate reason that sounds good and spares your feelings but masks the actual reason. Having knowledge of the real reason you did not win the business means you can make a better tweak next time. Falsely attributing the reasons for why you lost the business can falsely inform a scarcity mindset and lead to bad outcomes. 

Adding the right amount of value. As a great salesperson, I’m an educator in chief, thought leader, and product expert. When I meet with clients, I try to deliver value in each interaction. In these situations, I’m not “selling”. It’s painful to deliver value with some prospects and never land a sale or receive a referral.

Even though I expect it, I do not like the way it feels to not hear back from someone I reach out to in an email or by phone. It’s a rejection and though I know not to take it personally, I still do (a tiny tiny bit). So when I’m in hardcore sales mode and reaching out to a lot of people, it feels really vulnerable.  

I hate being a second (or third) bid. I’m skilled at knowing when a prospect is truly interested vs. pumping me for information/expertise and not likely to buy. Sometimes we have to graciously run through the motions and provide a quote or a proposal to someone who may not be ready to buy. But if we don’t cooperate, they might not partner with us again. 
As the seller, I don’t want to assume low probability of closing the sale because once I do, I know I’ll discount the opportunity and put less authentic effort into it…which virtually guarantees that I won’t close the business.

Talking too much. 70/30 is a good ratio of listening to talking, but what if I need to speak more to explain my product or prove that I have the requisite skills the prospect needs to make their decision. Push too hard, and you might offend. Push too little, and you might not impress. It’s a balancing act and it’s stressful (and fun).