Being a cabin crew, especially one for an airline as distinguished as Qatar Airways, requires a lot of work. You need to be outgoing, respectful, attentive, dedicated, empathetic, hardworking, cheerful, upbeat, and a good problem solver.
You should be able to give clear instructions, especially regarding safety, while at the same time maintaining a respectful demeanor. Do not be afraid to speak up, but never yell or overpower other people. You should be aware of passengers needs, and try your best to anticipate what they might need or want. Be sensitive to their needs. For example, even if your'e busy, if someone asks you for water or something say "Of course sir / mam, I will get it to you as soon as possible", never say "I'm busy". You should never slack off, and even if the task seems impossible, you should try your best to do it. When a problem arises, do not sit around and do nothing, come up with good ideas and listen to other people's input. Always smile, as hospitality is one of the key elements. Never make someone feel unimportant or unwanted, and never look down on someone.
You will probably need to rephrase it, and add your own bits. Its all about how you act. Be calm and respectful, while also being firm. Do not let people walk all over you, but also listen to other people's ideas and needs. Its about balance, basically.
Good luck. Remember, even if you do not make it the first time, try and try again!