The ShikkerDovid used to say that he wakes up every morning and gooes to shul and says to Hashem: “Hashem, please don’t kick me in the head today.” Some days you go to shul and feel like you are literally begging for your existence. You go to shul with a grocery list and implore Gd to fill the list.
The Talmud tells us, this does not work. On Page 55A, (at the top) the Talmud tells us those who prolong or extend their prayers, in the end will come to heart ache. The Talmud cites a phrase “Prolong prayer makes the heart sick.”
How is that possible? How can prolonged and spiritually infused prayer cause heartache. The answer is the type of prayers or the “grocery list” prayers. When we come to shul with an agenda and our “wants”. That there are no promises. As the Rosh Yeshiva of Oraitya says famously, the prayer is “Shma Kolanu” or hear our voices, it does not say, hear our requests and grant them.
Frankly, this is tough stuff. Easy to write. Hard to digest. If Hashem really loves me, he will not want me to suffer, lose sleep, walk around with my stomach in knots because life is so overwhelming. THere is no answer. So do we spill our guts and soul when we pray? do you do some perfunctory, distanced prayers? Maybe the answer is in the work “prolonged” (maarech). Our prayers dont need to be long to be effective. Maybe prayer is like pate or frois gros: short, small portions, rich and intense. Who knows? If somone figures out the secrete-please tell me.
ShikkerDovid 
I think the gemara explains that when you go to shul with your grocery list and expect that everything should be granted, Hashem looks at your merits to see if you deserve them first. We probably don’t, which is why we don’t get everything we ask for. It could also be that what we want is actually not what we need and what is good for us. So if you are expecting it, you won’t be happy.
The gemara also says that one who davens doe a long time will have a long life. How does the gemara resolve this. It says that it is talking about someone who offers supplication. I think the purpose of Tefillah is to connect to Hashem. It’s not about the gifts that we receive as a result. Rather it is about the actual asking for them. Hashem doesn’t need our praise. Tefillah is for us to talk to Hashem and establish a relationship with Him and build emuna. Then, once you have emuna, you don’t need to worry about anything else.
Brilliant!!