Some of the thoughts suicidal people have are because they do not want to depend on meds to control their depression in the first place. Even with the meds it is a constant roller coaster of ups and downs.
Not knocking what QK said but with chronic depression people are not able to feel the emotional lift of doing those things like ''normal'' people. The meds often dull the senses that may leave them with that empty feeling also.
There is no magic bullet unfortunately.