How To/Should We Constantly Be Altruistic?

I don’t necessarily mean happy without pause, but given a circumstance where we don’t like someone but may have to work or live with them or, as is the case often with international conflict management, we have to collaborate with those who we directly oppose.

Should we maintain altruistic qualities when faced with such emotional fatigue? If so, how (what steps can one take to be forever consistent in altruistic qualities)?

Or is it human to need a break from confrontation and instead surround ourselves with the known and comfortable (e.g. likeminded people)? If so, how much is too much of a break from confrontation (the fallacy of ‘yes men’ or apathy)?