Down, down, down... these days do come

I thought that I was walking on snow, but I fell right to the bottom as I took my first step.

I thought that mountains are never too high, but now I realise some obstacles are beyond sky's limits.

I am a can of Coke without gas;
I am a coloured balloon running out of air;
I am a withering flower in the middle of summer.

Down, down, down... these days do come.