I've been in exactly this position in the tech industry. Your boss is training you on the 'what to do' relating to being in warehouse management. What it doesn't sound like he's training you on - but that you could do outside study work on - is "How to deal with workplace stress". There's an entire industry devoted to this topic, but there are some simple things you can do. Things that work for me are:
0. Spend some intentional time to find self-training on dealing with workplace stress. Make this an on-going learning process. Have 1 or more de-stressing-item(s) on your to-do list daily.
1. Keep a 'to-do' list - put all your tasks on the list as they come up.
2. Put time-estimates with the 'to-do' items.
3. Prioritize your to-do list giving top priority to the 1-or-2-minute items to improve your daily accomplishments. (ex: reply to 'that email')
4. Realize those things you have control over, and those you DO NOT. Do *NOT* take responsibility for things you have no control over.
5. Learn to "Pick Your Battles". There are some things we'd like to get done that fly in the face of team/company culture. Other things can be easily accomplished by getting the right people on-your-side, or having the 'guy with a shovel next to the smoldering stump'. When picking your battles, choose to do the latter. If you must choose the hard things, break them down into bite-sized chunks, and attack them 1-bite-at-a-time.
6. ALWAYS be training your replacement. If you move up, pick a replacement on day 1, and start training them to do the job you're doing even while you're still learning the job. How do you know who'll be the best replacement? Two factors I look for in a replacement: 'hunger', and 'grit'. Does someone want to improve themselves, the work, and those around them? That's 'hungry'. Do they keep working at things until they get them done? That's 'grit'.
7. Treat your employees the way YOU want to be treated. This is the best way to build a team of allies who will help you move mountains.
8. Call 'bullshit' early and communicate broadly. If someone is asking the impossible, or something that's above-and-beyond, call it out right away, and don't be shy about communicating WHY it's such a out-of-the-ordinary request. You can still work toward the goal, but let them know that achieving it is 'above and beyond' the abilities of mortals.
9. Don't be so serious - keep humor in-the-mix at all times.
10. Before hitting 'send' on your emails, take a moment, and re-read your message from the point of view of someone who has NO IDEA what the message is about. Is it still clear? Are there things that could be mis-interpreted? (i.e. the word "resent" could mean "I re-sent an email to your inbox", or "I resent [re-zent] the way that message was communicated") Can you say it in fewer words, and still be clear? Improving office communications is the other big management 'industry'. You can do your own research, and solve >80% of the issues before the become a problem.