There's all this focus on persistence when it comes to success whether it be in business or love or anything else with a goal attached. But if there's one thing I realized, persistence alone is not just some magic ingredient you throw into the pot and voila, ze soup she ez done! That's a very naive thought process and one that I myself have been guilty of in the past.
Probably the biggest factor in success is timing. Applied to sales you can have the right product, the right attitude, and the right everything, but if the customer cannot buy for a legitimate reason, then no amount of persistence is going to change that, instead you're just going to poison the prospect if you do persist (also guilty, hehe). Apply this to life and I believe this is really enough proof that some things are meant to be, and by necessity, some things are not...at least for right now.
You can look at it spiritually if you want as well, but in terms of logic this supports that belief if you prefer to look at it that way. Just because you have the right ingredients, the right recipe, and the right oven temperature does not guarantee making a great cake anymore than increasing your odds guarantees success. It also takes that extra element of timing. When I did Judo many years ago, a black belt told me ever since becoming a black belt, it's not his throwing technique that he works on, its his timing...why do I throw, not how do I throw.
That being said, I do not endorse sitting on your ass when the going get's tough and saying "oh well I guess its just not meant to be." Timing is not an excuse for surrender, it's a fundamental truth for peace of mind. Whether something is meant to be or not is not for us decide, but a result of the present circumstances. Our job is to persist within reason, with peace of mind in the truth of "if not now, then later."