The Scots have not reached the finals of a major tournament since the 1998 World Cup and, despite a late flurry in their qualifying group which ended with three wins in their last four games, they will again be spectators when the 2014 tournament takes place in Brazil next summer.
Everton forward Naismith and the rest of the Scotland players will have to kick their heels for the best part of a year until the Euro qualifiers begin, and in the meantime will have to play a series of friendlies starting with the visit of the United States to Hampden Park on Friday.
That is followed by an away game in Norway next Tuesday, and Naismith insists the momentum built up under Strachan will have to be kept going until the competitive action begins next year.
"It is important because the squad is getting to the mid-to-late 20s stage," he said.
"You have got to be hitting your peak at some point and that has to come from now.
"We have started from a good base and it has got to continue.
"The results we have had have been brilliant. We have moved on a long way but the real test will be when the Euros start and we have to be ready for that.
"Yes, it was very disappointing that we couldn't qualify (for Brazil). It hit him home very quickly but it has probably driven the boys on as well.
"We don't want to be in a team that is one of the first to be knocked out of the qualifiers, so there is a lesson to be learned.
"There is a bit of wait (until the Euro qualifiers begin) and that is the disappointing thing for the squad and the manager.
"But overall, we have to keep this momentum going with good results. We have two tough games coming up that we need to be on song.
"They are not just friendly games, everything goes to your ranking as well so there is always something to play for.
"The USA are a really good side, they have got real quality.
"We are going to test ourselves against a team who is going to the World Cup so it will be an interesting game."
Naismith believes the fundamental reason for the recent good results and performances has been Strachan's confidence and belief in his squad.
The former Kilmarnock and Rangers player, who was in Glasgow to help launch an initiative with Glasgow's Helping Heroes, construction firm City Building and Royal Strathclyde Blindcraft industries, which will help injured war veterans back to work, said: "The manager has done well in finding players who were not on the radar. Ikechi Anya came in and done really well and there are a few others.
"But the biggest thing he has given us is the freedom to go and play.
"We have quality players going forward and that is what he has done, given us the belief.
"If someone does try a forward pass and it doesn't come off, he is not at the sidelines shouting his head off or anything like that, he is encouraging you to go again.
"He has been thorough in training in what he wants and the players are definitely picking it up."