It's tempting to step in and solve your friends' problems for them.
But if you do something that your friend should do themselves, then it creates dependency and it makes it easy for them to take advantage of you.
During my college years, a classmate didn't do his part of a group project. Instead of telling the teacher, I just did his work for him.
As you might guess, during the next project his work was once again incomplete, and I once again felt the need to step in and do his job as well as my own. Once I confronted him and told him that I would no longer cover for him, his work magically improved.
Of course, there is a balance here. Sometimes taking some responsibilities off a friend's plate can provide them with a big boost.
A few years ago, I was moving and felt very stressed about getting everything done. My roommate took the iniatitve to dissasemble my desk and prepare it for moving (a major project that would have taken me a lot of time.) His help really reduced my stress levels, and made me feel cared for and supported.
So I'm not saying that you should never do something that your friend can do for themselves. Instead, I'm warning you to look for patterns.
If you start to feel obligated to do something for your friend that they should normally do for themselves, or if they expect you to do things for them while they laze about, that's a sign that you probably need to rethink how you support that friend. If you're not sure, try saying “No” sometimes and see what happens.
In addition, be careful to maintain good emotional boundaries. You need to be able to live your life even if your friend is struggling. If you can't feel happy as long as your friend is struggling, or if you feel personally responsible for your friend's recovery, it's likely your boundaries have collapsed.
Remember, you are not responsible for your friend. Your friend is responsible for themselves.
Decide what is appropriate for you to give, and trust your friend to do the rest.