Traveling is my passon. I have been working abroad and traveling for the past 3 years straight with no idea when I am going to stop.
Traveling can be a wonderful experience. The planning before a trip gets you excited. You plan your every move right down to the restaurant you are going to eat on the third night of your trip. Everyone's going to be happy the whole time and there aren't going to be any delays or problems.
First of the five essentials of being a happy traveler is that you cannot be< hungry. This is a big one. Some people turn into different people, monsters really, when they get hungry. Have you seen those Snickers' commercials? I don´t suggest you get a Snickers though to fill you up. Pick up some healthy, cheap, travel friendly foods before beginning any plane, train or bus journey.
Second, you have to keep hydrated. Make sure you drink lots of water. This could be hard if you are traveling because it is so easy to forget to drink. Keep a reusable water bottle on you at all times. If you are lucky enough to be in a country that you can drink the water you can refill the water bottle at water fountains. Alternatively, you can buy water bottles. You will have to do this when you are traveling in places since water is not always safe to drink from the tap. The cheapest option is to buy the biggest water bottle you can find but this will be heavy and hard to carry. It might cost more to get smaller water bottles but it will be well worth it to be well hydrated. A normal person should have 2-3 liters of water a day. If you are traveling and walking around you should aim for at least 3 or more liters. Now, I have been talking about water the whole time. This is important because water is so good for you. Soda is not a good option. Soda has been proven to make you feel dehydrated and there are no nutritional benefits. Remember lots of food contains water as well for example: Watermelon and pineapples.
Not being too hot or too cold. This is a big one for me because I am always cold like, always. I can be in Bali in the middle of the summer and my hands will still be ice cold. This is a problem when I am traveling with other people because I like to keep the heat on max and that doesn't fly too well with normal warm blooded people. So, most of the time I have to just deal with being cold.
Not being wet. This is similar to being too cold except you are wet. No one is happy when their shoes are soaking wet and you are five miles away from your hostel. Even having an umbrella helps a little. The best thing to do when it starts to rain is get inside. Or do an indoor activity.
Finally, make sure you get enough sleep. This can be so hard when traveling. You are not in your own bed, you have to get up at weird hours to do a certain tour, you are jetlagged, you want to party all night, the people in your hostel partied all night and woke you up at 4 am, etc. I recommend earplugs and a good alarm clock.
Keep these things in mind when traveling with a group of people. You have to make sure everyone is happy so if something does go wrong it's not as big of an issue. If I have these five essentials and my plane is delayed, I am not going to be as annoyed.