There is a fine line between perseverance and choosing another approach. Let me explain.
If something (e.g. your marketing campaign; your sales calls; your partnerships) is not working, you should not stop after having tried it just a couple of times. You really need to give it some time and analyse the various reactions and perspectives. It is good to not give up and persevere.
But there comes a time when you have to reflect on your approach if there are no results. If you have the feeling that you have given your (old) approach a fair chance, then it is time to change the course. Develop a new approach and go for that. The timing is crucial. If you stick too long to a not-working approach then you become stubborn and frustrated.
However, you need to get the juices flowing again! So, stop when you are starting to feel frustrated and cynical. There are multiple roads which lead to Rome.
What is your new road?
GROW YOUR PEOPLE, GROW YOUR BUSINESS!