Along with hundreds of thousands of others, Ho Ka-ying attended the July 1 march - but he was not concerned with political issues. He came instead with a supply of oxygen cylinders. Mr Ho was one of 200 St John Ambulance members who set up various first-aid posts along the march route. If these volunteers had not provided their services, the 300 people who needed treatment might have had to face the severe consequences of overheating. 'It was exhausting,' says Mr Ho. 'The necessity of our services exceeded our expectations. Our posts nearly ran out of medical supplies mid-afternoon when the heat was at its peak.' The oxygen cylinders were used to calm victims down in the heat. Mr Ho says as long as it doesn't jeopardise their normal jobs, members are more than willing to help. 'I didn't mind working on a national public holiday. After all, we devote our leisure time to working for the public.' Mr Ho, 50, has been a dedicated volunteer for more than 30 years. 'I joined in secondary school. Somebody told me that whether you can allocate your time depends on how important you think the issue is. I think helping people is important. And I deemed the people who needed assistance most to be the wounded and the sick.' The organisation includes a mix of students, middle-aged citizens and highly experienced seniors. Students as young as 17 can join, as long as they pass the rescue, home nursing and first-aid training courses. Mr Ho is currently in charge of the ambulance transport and communications section, as well as the emergency response team. 'We're the spearhead of the operation. I love the hands-on experience of facing the public. That feeling that you've actually saved somebody ... nobody can take that feeling away from you.' When Mr Ho retires from his full-time job as a customs officer, he hopes to continue his volunteer career with St John until he reaches the service's retirement age of 70. 'After 30 years of service ... St John Ambulance is now like a second family to me,' he says. 'People join because St John provides an opportunity for us to fulfil our common desire to serve society. We are birds of the same feather - we flock together, naturally. Once the bonds of a common goal are built, no one wants to leave, especially as we've been through many difficult times together. 'When you have to choose and judge which patient to take care of first, that's when you realise that someone's life is in your hands, and if you make a mistake, people die.' Fortunately, throughout his 30 years of service, Mr Ho cannot recall making any serious mistakes. 'In such critical moments, one has to be very confident about his or her training. 'I'm an ordinary man, living an ordinary life. I'm not Rambo or anything like that. You just never know what may happen to you tomorrow, so every day I must feel like I've done my duty. It makes me happy that I've done my job.'