What is it that drives you to push yourself when PT'ing by yourself?

Hello RallyPoint, I hope everyone is well today. Aspiring to enlist with the Army in the next year or two, I have already begun PT'ing myself on a daily basis. I intend to ace my PFT when I get to basic because to me, nothing else is acceptable on my part. It is not so much me wanting to be snobby and score 300 all across the board on my PFT just to do well, but it is more of what I believe is the right thing to do. With that said however, in the past few weeks, I've only been able to shave a minute and fifteen off of my original time (14:30) down (to 13:15) on just a SINGLE mile run, when I know I have to do double that for the PFT (13:15 for two miles). My push-ups and sit-ups can always use improvements, but I am overwhelmingly disheartened by my running capabilities most of all. I was never a runner, not even in high school (when I was decently fit) was I a runner.

I am 40 lbs. over the weight standard and probably a good percentile over the BMI standard as well, but I am not noticeably obese, I have a small bit of a gut, but that's it. I can't help but give in to my mind every time it incessantly screams for me to stop when my throat, lungs, and muscles are burning to the point of projectile vomiting. In a sense, I did make the perfect score time of 13:15 (for my age group) on my last run time, but only at half of the work (only one of two mile). I can't help but look at that and consider how ironically pathetic it is that I only can make the perfect score time with only half the required distance. Today for the first time on my daily run, I actually stopped two-thirds of the way and just gave up. I see the weakness in my mind, but I am at a loss and don't know how to close with and engage it. Running is crucial to PT and PT is crucial to the military, when I'm not wheezing and puking from running and have time to catch a breath, I keep telling myself that I won't tolerate this weakness from within myself, but every time I projectile vomit or dry heave when I run, it brings me into doubt once again. There is a friendly running group that I know of, but due to current events, they've been offline for a while. Hopefully they can help me with my weakness.

Meanwhile on here, I figured it wouldn't hurt to ask for wisdom and knowledge. What I'm mostly asking is, what is it that you do or use to help push you through those times when you want to give up, when your mind just keeps screaming at you about how much this sucks, and how you actually physically “embrace the suck”? For someone that is not in the military yet, how does one get himself not just physically, but mentally prepared to do what they have to?

Again, I hope all is well with everyone.