NAHT Cymru's new president Terry Williams urged heads to "always look on the bright side" despite the cuts that schools are expecting to face.
In his address to the union's annual conference, Mr Williams, head of Litchard Primary in Bridgend, said it was important that heads did not allow themselves to be engulfed by "doom and gloom".
He told TES Cymru: "There is so much happening at the moment, I think it is important that we rise to the challenge; we are can-do people.
"We know budget cuts are going to be gruelling, but we can't get too gloomy; there's always a light at the end of the tunnel."
Talk about the school effectiveness framework (SEF) dominated the conference, held in Pontyclun, after education minister Leighton Andrews labelled an NAHT Cymru survey that revealed its members' concerns about the policy as "baloney".
During a policy debating session members were split on the subject, with some complaining that the survey had been "very damaging" to the union.
Mr Williams said NAHT Cymru was not opposed to SEF, but there was a lack of awareness about its aims and how it was going to work in practice.
In his address to the conference, Mr Andrews repeated his message from last week's TES Cymru in which he called SEF a "route-map" that would guide Wales to better performance.