Cutting out fizzy drinks, coffee or alcohol is something that everyone at some point has told themselves they will achieve.
But when was the last time you had a latte or a coke? Probably this morning, right?
There are a number of health benefits to going water-only (especially in a heatwave), as Chris Bailey found out when he drank only H2O for a month.
Here's a brief breakdown:
1. You'll consume fewer calories:
A cup of tea with sugar will set you back around 30 calories. A morning mocha will set you back around 250 calories. A 500ml bottle of Coca Cola contains 210 calories.
Water? Zero calories. And obviously it's more hydrating, it's water.
2. You'll appease your appetite:
Water will suppress your appetite - after all, you may not be hungry, you just might be thirsty.
3. Your brain will work better:
Your brain is around 75-85 per cent water. Stay hydrated and your brain will keep working happily.
It'll help your concentration and your energy levels. So if you have a maths test, stay hydrated.
4. It's cheaper:
You won't be the only one healthier, your wallet will be too.
5. It fires up your metabolism:
When you drink water first thing in the morning, it fires up your metabolism for the day. Researchers found that drinking 500 ml of water increased metabolic rate by 30 per cent in men and women.
In short, get the motors going to start the day with a glass of agua.
6. It'll clear up your spots:
The folklore has rung true with a large body of evidence, switching from sugary drinks to water will do wonders to your complexion.
It'll help bring moisture to your skin and will stop headaches from dehydration - which will help with those crows' feet.
7. It'll help you on the loo:
Water helps keep you regular and, combined with a high fibre diet, leads to top-quality toilet trips.
You may be going more frequently for your bladder, but that's no bad thing.
8. It'll help your heart:
If you're exceptionally dehydrated your blood is thicker and your heart has to work harder to pump it.
A study by Eden found that drinking more than five glasses of water a day cut chances of a heart attack by 41 per cent, compared to less than two glasses a day.
They sound like great odds to us.
9. It'll help your workout:
You're not at your Herculean best if you're dehydrated.
If you want to smash a PB, stay hydrated.