Changing your own bad habits is challenging, but helping someone you care about improve their lifestyle might be even trickier.

Whether it's your spouse, your kid, or your colleague who wants to change, there's a fine line between encouraging and browbeating, bullying and holding someone accountable. How can you strike the right balance?

First off, swear off nagging. As Stanford psychologist and motivation expert BJ Fogg has explained, it's completely ineffective.

"It may be that you have somebody that you're married to or someone in your family that you think needs to get more active or eat better or what have you. What you will probably be incredibly unsuccessful at doing is nagging them until they get it done. It doesn't work," he has warned.

But once you've given up nagging, what should you replace it with if you're still eager to help? Author Gretchen Rubin offers a whole host of helpful suggestions on her blog, including:

1. Make it more convenient.

Human beings, I'm sure you've noticed, like to do what's easiest. You can use that harsh truth to your advantage whether you're trying to help your co-worker beat their multitasking addiction or your sister kick her junk food habit, explains Rubin.

"Can you leave a pill out on a dish by the coffee machine, so your sweetheart takes it every morning? Can you keep a bowl of hard-boiled eggs in the fridge to be an easy, healthy snack? Can you pull out a pile of board books, clear off the sofa, and say, 'Would it be fun for you to read to the baby for a few minutes?'" she asks. (As a side note, Fogg also enthusiastically endorses this approach.)

2. Be the scorekeeper.

We all know the old management maxim, "What gets measured, gets managed." But the same principle generally applies to life in general too. We're more likely to keep to a new regime if we define exactly what success looks like. So, "I'm going to the 1:15pm exercise class at the gym across the street three times a week!" beats "I'm going to start exercising!"

You can help your friends and family stick with their new program by helping them set and keep track of these sort of specific goals, suggests Rubin.

3. Provide a little pessimism.

Wait, why would you want to talk about all the ways the other person could fail? Because, Rubin notes, anticipating likely obstacles and planning for them makes you more likely to succeed at changing your life.

"You can help someone else to anticipate difficult circumstances, and to come up with an 'if-then' plan of action -- whether for the holidays, for the office party, for the vacation, for the bad weather, or whatever it might be," she asserts.

These are the three techniques that Rubin suggests will work to help nearly everyone. But if you check out the complete post, there are a lot more strategies that Rubin prescribes only for certain personality types, along with tools to help you understand which type you're dealing with.