Identify the warning signs without interpreting them
Changes in a person's ways of working and communicating may draw
our attention and cause us to say "he/she is not doing well." The
causes may be multiple and complex; it is better to avoid
imagining or interpreting them. The question "is it your
personal problems that are preventing you from concentrating?" may be,
with good reason, very poorly perceived. It is likewise
preferable to note what is different (what has changed) and to
express it as a simple observation, without any attempt at analysis.
Permit expression without insisting on it
It's not easy to find the balance point of distance/proximity at
which one feels in one's place as a manager and also humanly
benevolent. The co-worker may wish to share his problems and to
be understood in his difficulty facing them. In this case it is a
matter of listening, without judgement or advice. Listening without
forgetting the context in which you listen -- that of a
hierarchical relationship rather than a bond of friendship --
and so being attentive that the co-worker not go too far in sharing what
may not be useful to us and which he might regret
later.
Inversely, if he does not wish to share his worries, then you
should respect his reserve. There's no need to know exactly what is
happening, in order to support him.
Envision holding his post in the current situation
It is possible that personal problems have no impact upon
performance, or that the co-worker does not want any adjustments or
help. In the case where, on the contrary, adaptation is
necessary, several questions: "In the current context, what
could help you? How do you see your work at this time? How do you
envision the coming weeks? What do you expect from me? ..."
Supporting a co-worker in his post is a discrete way of supporting him more globally.