If you’re a real fitness addict, you certainly know the ultimate running challenge is to take part in a marathon. It seems every major city and town around the world hosts an annual marathon, with thousands of athletes running an exhausting 42.1 kilometres. While many runners’ motivation is to beat their personal best and cross the finishing line without collapsing, they’re also doing it for a good cause — to generate funds for charity.

But like other major events, the marathon also generates a massive carbon footprint. Thousands travel – some by plane — to the location, and waste from food packaging and goody bags gets left behind by viewers and runners.

This is becoming a big issue for cities — how to host a worthwhile event, encouraging people to exercise and help charities, while protecting the environment? Several cities have developed formal plans to reduce their environmental impact and promote sustainable ideas. One event in Wales, for example, introduced recycling for old running kit. It’s something that this year’s London Marathon tried to tackle by reducing the number of drink stations on the running route, giving out water in paper cups and offering some drinks in eatable seaweed capsules. They also trialled new bottle belts made from recycled plastic, so 700 runners could carry water bottles with them during their run.

Meanwhile, some people still think running a marathon could be our best foot forward in helping the planet. Dr Andrea Collins from Cardiff University told the BBC: “Training for a marathon makes you more sustainable in day-to-day activities. I started walking or running to work every day. Being environmentally friendly while training kind of sticks with you and becomes a way of life.”

So while you may not be the top runner in a marathon, let’s hope the event, in terms of sustainability, certainly is!

We all agree that we should recycle more at home, in the office or when out and about. 【小题1】 As a result, they can be collected and taken to the right place for recycling. This is what the process of sorting allows us to do.

【小题2】 And the effective sorting needs to happen first in our own home, and second in sorting plants to which waste is collected. When you put a plastic bottle in the right recycling bag or bin, you are helping sort recyclable things so that the right material can be fed into the right recycling process. If sorting does not happen, a lot of recyclable materials can end up in landfills. It will lead to valuable resources lost from our economy.

【小题3】 For instance, in Brussels consumers put plastic packaging, cans and soft drink cartons in blue bags designed for recyclable packaging; paper in yellow bags for recycling; and glass needs to be taken to specific collection bins. Somewhat differently, in Vienna(Austria), citizens can expect their paper, metal, glass and plastic to be separately collected in different weeks of the year. 【小题4】.

Once recyclable materials are collected from your home, they are further sorted in specialized facilities which ensure the quality of the recycling process. 【小题5】 Traditionally, sorting has been done either by hand with workers sorting what can be recycled and picking out the materials to be thrown away. Today, however, new sorting technologies are being developed in order to speed up the process of sorting but to also cause better results. Exciting technologies using magnets or optical systems are being used to effectively sort materials so more of them can be recycled.

【小题1】   However, whether you are on the mountains, in the waves, or on the grassland, you should be aware that your sport of choice might have great influence on the environment.

Some sports are resource-hungry. Golf, as you may know, eats up not only large areas of countryside, but also tons of water. Besides, all sorts of chemicals and huge amounts of energy are used to keep its courses（球场）in good condition. 【小题2】 For example, in the dry regions of Portugal and Spain, golf is often held responsible for serious water shortage in some local areas.

【小题3】 Power walking is one of them that you could take up today. You don’t need any special equipment except a good pair of shoes; and you don't have to worry about resources and your purse. Simple and free, power walking can also keep you fit. 【小题4】 Experts say that 20 minutes of power walking daily can make you feel less anxious, sleep well and have better weight control.

Whatever sport you take up, you can make it greener by using environment-friendly equipment and buying products made from recycled materials. But the final goal should be “green gyms”. They are better replacements（代替物）for traditional health clubs and modern sports centers. Members of green gyms play sports outdoors, in the countryside or other open spaces. 【小题5】 And best of all, it’s free.