When I am in a really severe depression none of those little behavioural things like going for a walk in the sun help me. Therapist have all their little suggestions on get up a 7am eat a good breakfast, take a shower, go for a walk, etc, etc. Don't work for me. Can even make it worse because when i can't do what they asked me to put on a list I just feel ashamed. If I am in moderate or mild or coming out of one those things do help but not with real severe.