Am I severely out of shape?

i was mowing the yard today, its pretty large, with a push mower. its 90F today, about 30 minutes in i felt like i was going to collapse. it was a weird sensation, kind of like i ran a marathon, started getting a weird feeling in my neck, kinda like a muscle was spazzaming, also felt like i was going to puke. i took a break for maybe 1-2 minutes, in the A/C, then i felt almost 100% better, and i went out to continue and about 15 minutes in it happened again but worse. when i mowed the lawn when it was cooler out this never happened to me. i did wear a crew neck sweatshirt because im out of sunblock, buy midway through i took it off. am i severely out of shape? i didn't feel anywhere near this bad when it was cooler outside and i could knock the front and backyard out at one time. this time i needed 3 breaks. i kinda still feel sick. by the way i am 25 year old male

Am I severely out of shape?
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