A good introduction is an essential part of your essay - it's also veyr difficult. If you know in your head basically how you're going to answer the question then you can develop a thesis. this is essential for the introduction. Basically, you need 2-3 sentences giving what texts you are oing to discuss, your overall approach to the question (your thesis) and it helps if there's some indication - it doesn't have to be blatant - of how you define journey: or, in your particular case, what the concept of physical journey means; this determines how you will approach any questions discussing journeys (for example, is physical journey only concerned with movement through space? or is it also movement through time? can it be a catalyst for other inner, imaginative, emotional or spiritual journeys? Are they limited to one person or can they be shared? These are a few things to consider)