"I'm fiddling"
(You get an 'A' if you know what movie this is from!)
Are you a fiddler? I'm the type that will fiddle with something in my hands when I'm thinking, conversing, listening...it's just something I mindlessly do with various objects nearby. I'm usually not actively thinking about it. My hands seem to have a mind of their own in that way and before I know what happened, I look down and realize I've unscrewed the pen tip or I'm twirling my wedding rings around my finger.
Infertility can be like that. Without even realizing what happened, you can find yourself going from carefree to fretting. You can find yourself obsessing about one tiny detail or following the thought pathway of a particular what-if scenario.
I've come to realize that the enemy uses these "mind fiddles" as an opportunity to decrease your faith. Because when I have that moment of realization that I've been fretting about something, I realize that I feel more hopeless and alone. The enemy uses those opportunities to draw you away from God.
So it's very important to faithfully and continually evaluate yourself. If you realize you're fretting or that you've started claiming the reins of your life/situation thinking you have control over something that you really don't...release it. Give them back to God.
1 Peter 5:6-11
6 Therefore humble yourselves under the mighty hand of God, that He may exalt you at the proper time, 7 casting all your anxiety on Him, because He cares for you. 8 Be of sober spirit, be on the alert. Your adversary, the devil, prowls around like a roaring lion, seeking someone to devour. 9 But resist him, firm in your faith, knowing that the same experiences of suffering are being accomplished by your brethren who are in the world. 10 After you have suffered for a little while, the God of all grace, who called you to His eternal glory in Christ, will Himself perfect, confirm, strengthen and establish you. 11 To Him be dominion forever and ever. Amen.
It's unfortunately not a decision you just make once; it's a decision you have to keep making throughout your journey (and whole life, I would argue). Let it go, and put the reins back into God's hands. Take charge of your thoughts, and direct them where you know they should go.
2 Corinthians 10:3-5
3 For though we walk in the flesh, we do not war according to the flesh, 4 for the weapons of our warfare are not of the flesh, but divinely powerful for the destruction of fortresses. 5 We are destroying speculations and every lofty thing raised up against the knowledge of God, and we are taking every thought captive to the obedience of Christ
Take ownership of what you do have control over, but nothing beyond that...you have to let those things go. It's worth it, because whose hands are more capable than God's?