1. Just because you can't physically see someone's suffering does not mean it's not there.

Chadwick lived a remarkable life, even during the past four years, and no one ever suspected he was ill. However, that doesn't change the fact that he was. I think it's important to remember that, no matter what the illness is, just because you cannot see someone's pain does not mean they are not battling something internally. Be there for people. They may need a shoulder to lean on, even if you don't realize it.

2. If you try to make plans, and they decline, respect their decision.

Whether or not you know this person is battling an invisible illness, you should be respecting their decision. Most of the time, no matter how close we are to someone, we don't really know everything they are facing on the inside. Especially if we cannot see it from the outside. If someone says they don't want to hang out, respect that. If they are suffering from an invisible illness, they may be feeling unwell but not want to tell you. Believe them (even though you probably can't see what they're feeling), ask if there's anything you can do, and show them respect by letting them rest.

Because hey, we all need time to rest anyway.

3. Remember, someone's illness is not their identity.

This is so important to remember, and something Chadwick's battle clearly reminded us of. As aforementioned, he lived a remarkable life in the past four years. He filmed multiple movies, went to red carpet events, and visited young cancer patients at St. Jude's. He did phenomenal things, and his illness didn't hold him back.

The same can be said for my grandpa, too. He kept living his life to the fullest, as much as possible, each and every day. And while we recognized the battle he was facing internally, we also recognized the happiness he exuded.

Don't let someone's illness cause you to underestimate them. Someone's illness is not their identity.

4. Check-in with people, but don't offer advice about something you don't really understand.

"How are you doing?"

As simple as that — a quick check-in that doesn't make the person feel like their identity revolves around their illness but allows them a chance to talk and feel loved. Showing you love and care is one of the best ways to be there for someone facing an internal illness. I know nothing made my grandpa happier than receiving a phone call from his grandkids.

However, if they tell you they are not doing well or not feeling well, do not offer advice on what they should do to feel better. Because, the fact is, you don't know. This is a battle only they can see, and you can't fight it with them, but you can support them. Give love, not unsolicited advice.

5. Don't ever take someone for granted.

I think the most important thing Chadwick's battle reminds us of invisible illnesses is to not take anyone for granted. Just because someone is carrying on in their day-to-day life and looks perfectly healthy does not mean they are.

I never once took my grandpa for granted, and still, I wish I could give him one more hug. An invisible illness took my grandpa, Chadwick, and many others, even though these people looked healthy and happy on the outside. Someone does not need to be visibly ill to be ill, so whether someone you know is battling an internal or an external battle, give them an extra hug today. Life is so important and so precious, and we must never take it for granted.