Here's a useful habit to develop...if you haven't done so already - Get used to "dialing up" to your optimum effort level. That is to say...start slow and keep adjusting the dial up (faster) to find your speed. It's so much easier than dialing "down"...going out fast and slowing down to find the best pace. This applies in races or workouts.
When you "dial up," you let your body find the right pace. You enter into a dialogue with your body. It's sort of like asking your body to perform in a polite way...rather than using the heavy-handed approach of bludgeoning your body by starting too hard.
In races...you have less room for dilly-dallying. You can't dawdle around too much...especially if the race is shorter. But if you've done a proper warm-up...you can dial up the effort during the race simply by going just slightly slower than your anticipated pace in the first 10% of the race. Your body will tell you precisely how fast it can run. And you will still be giving it 100% effort.
In workouts...it's easy....head out the door like a snail and go from there. You'll eventually settle in to a pace that suits you...and it will be a lot more pleasant...and a lot faster....than it would be if you went out the door like a rocket.
It's mostly about patience...trust...and gracefully getting into the flow...while still doing your best. All good stuff.
PS Do these guys look like they are straining?