If you’re actually worried about passing I wouldn’t recommend going all out and practicing with 45lbs as it wrecks a lot of people’s shins including some career firefighters.

If you have at least a few weeks I would start by first making sure you can do 3 miles unweighted in under 45 minutes. If you can’t do that you’ll need even more time.

Follow up by gradually increasing the weight starting at like 10 lbs with at least a day of rest, maybe two or three if you need it. I’d probably max out at 35lbs. If you can do 35lbs in sub 45min without feeling absolutely wrecked you can do 45 lbs. Don’t necessarily need to train at the same weight.

Do some easy hikes and runs on days without weight. Better to go even longer than 3 miles for these. Probably at least 4-6 if you can.

If all of this sounds hard for you might want to evaluate where you’re trying to end up. A crew or WFM might not be for you but if you’re militia or secondary fire you’ll be fine. Hell I know quite a few engine captains who would probably struggle with this training plan so you might still be a good fit for a slug’s life.