How to get my child to be interested in participating activities? He loses interest very fast

Try involving him in a variety of activities. Observe which one he tends to lean towards and then build up from there. You can ask him directly what he would like to do and encourage his interests. Or from the things he does at home/say try to pick out some signs and just go with the flow

Try and keep him engaged as much as you can with different tasks within the activity? :) what type of activities are you referring to?

It is the phase he is going thru to find is correct interest.

How old is he? Let him take time to find his passion.

I think you can start by bring him to nature.