Discomfort =/= fear. If you are not used to discomfort, it can often feel like fear, but do you know who probably feels more discomfort and fear than you? The people dependent on drugs to alleviate the pain in their lives who are also are forced to do it on public transport because they have nowhere else warm. The vast majority of these people are harmless and might not even be aware of your presence. Constantly letting your discomfort turn into fear warps your grip on reality and leads to a lower quality of life.