If anything make sure you tell her/him/them that you're there for here no matter what. Ask if she/he/they are comfortable to talk about what's making her/him/them so upset, if she/he/them opens up listen carefully and make sure to give a constructive but kind response. If she/he/them doesn't feel comfortable don't try to force her/him/them. Tell her/him/them that you know she's/he's/they're strong even though she/he/they may not feel like it, and tell her/him/them you're always there for her/him/them.
Heat stroke can kill or cause damage to the brain and other internal organs, and is most likely to effect someone doing an activity like, Working out, playing soccer, playing basketball.