Approving (conscious endorsment) of a behavior reinforces it. However, it's pretty mild reinforcement.

High-effort behaviors get punished for being effortful. Strong motivators can reward them more than they're punished, so they end up reinforced overall. But approving alone can't do this, because it's too weak. So if you try to learn Swahili (high-effort) in the naive way, you won't, because the negative reinforcement from studying will overwhelm the positive reinforcement from approving of it.

There is no such punishment for low-effort behaviors, so approving can dominate here.

This suggests clever routes to approved high-effort behaviors: do something low-effort (like telling your friends), so mostly controlled by approval, that leads to strong reinforcement for the high-effort behavior (like getting made fun of for not learning Swahili).