Imagine you need to use the loo. Really, right now, you desperately need a loo.
Now imagine you're in Uganda, one of the poorest countries on the planet.
Now imagine you're in Uganda and you don't have the use of your legs. You don't have a proper wheelchair to get around with either - you use a hand-pedal bike, creaky and rusty.
Now imagine the only toilet is the communal pit latrine shared by everyone in your area.
Now imagine the others think your disability makes you dirty, and they might catch something if you use their latrine - not that using it is very enticing anyway, since the ground around it is fetid and you'd have to drag yourself across it to get there.
Washing afterward is difficult, too, since you can't reach the only water source, and you'll have to ask for help from people who may jeer or ignore you.
Remember, you still need that loo. Right now.
What do you do?
Tuesday, December 3 was the UN International Day for Persons with Disabilities - a chance to consider the myriad challenges facing disabled people and how we can make the world a more accessible place.
WaterAid transforms lives by improving access to safe water, hygiene and sanitation in the world's poorest communities.
We've begun a policy of promoting inclusive water, sanitation and hygiene projects to ensure these basic services can be used by everyone.
From our work around the globe - in Uganda, Zambia, Bangladesh, Mali, Madagascar and many other places -- we've found that often a very simple measure is enough to provide accessibility.
We've encouraged partners to install ramps into safe and secure toilets, create wider entrances and room inside for a wheelchair and carer to turn around, install simple handrails and even adapt a movable wooden toilet seat to make basic access easier.
We've also helped install rainwater harvesting jars near the homes of disabled people, so they don't have to wait for someone to bring them water for washing from a collection point.
These are all low-cost measures that can restore good health and immeasurable dignity to those using them.
"Getting this complex, with disabled friendly toilets and a disabled friendly water source has really improved our lives. In the past we would go to the toilet at the roadside or find an open space or drain," said Miss Poppy, a young woman living in Dhaka, Bangladesh, who has had her life transformed by a WaterAid partner project to open an accessible water and sanitation centre in her neighbourhood.
The ability to be more independent, and to keep herself and her clothes clean without being forced to beg for help, has brought her new respect among her neighbours.
You can watch her story here.
"Nowadays people show me some respect," she said. "Before I didn't have anyone helping me and talking to me. Now everybody wants to talk to me because they can see that I am well. They can say that she has no bad smell and that she is looking good."
What must come next for Miss Poppy, and others like her in the developing world, is to have their rights considered more broadly in aid and development projects.
The UN's Millennium Development Goals, a series of eight lofty intentions which, among other things, intended to halve extreme poverty and hunger, address the spread of HIV and other illnesses and address the plight of those without safe drinking water and sanitation, are to run out in 2015. It's clear they need renewing, and a debate is now underway to address how and when that will happen.
If we are to address extreme poverty as these goals promise, the thoughts, opinions and needs of people like Miss Poppy must be included, to ensure development leaves no one behind.