These days, every modern mobile phone has music playing capabilities. There is no better way to appreciate music than through a tiny mobile phone speaker. You will find that you can improve your phone’s bass reproduction by turning up the volume as much as possible.
Most people on public transport are music lovers and will therefore be delighted to participate in your public music sharing. For this reason, it is certainly unnecessary to invest in a pair of decent headphones.
The text message/email you are reading/composing is so absolutely, life depending, vitally important that you must continue to do-so whilst walking down the street.
You can normally do this by using the ‘walking at the speed of a stoned slug’ technique; where you meander down the street, totally oblivious to the tutting, frustrated commuters unable to overtake you on the busy pavement.
You can also optionally stop at random moments when your multitasking abilities run out, causing a minor pavement pile-up behind you.
(Thanks to cosmic_fish for the tip!)