
Like the others have said don't beat yourself up over it
This will sound a bit odd but I do some training indoors Picking him for a cuddle & popping his lead on then treating him & immediately take it off all in the safety of your arms whilst you are sitting down(I presume you allow him cuddles on your knee etc)
I would use a silly command like "Do we like Mr Leadie" when I did it. You will need to conceal the lead from him when you pick him up(possibly leaving it on the chair/settee etc)
I would also put the lead round a toy(especially if he has any cuddly toys) & pull it around saying nothing to him & if he goes towards the toy & especially if he picks up the to treat him immediately
You could use a chicker to mark the behaviour you want & then treat
He needs to see the lead as a source of pleasure & reward
As for the lift I would carry him to within sight of the lift & pop him on the floor & treat him & then pick him up again & take him home again very gradually getting closer to the lift & if he shows any sign of stress/worry move away from the lift.
I'm a great one for silly conversation with my dogs & if you don't mind sounding daft i would do something similar like this "does (puppies name)want to go walkies Does he want to go see(doggy friends name)in the park ? Shall we get mr leady ?(treat on the word leady & pick up puppy & pop on lead)Are you a good boy wearing mr leady ?(treat on the word leady & put puppy down keeping hold of the lead & walk toiwards your front dog If he gets upset stop go out to his level & holding a treat infront of him move slowly towards the door. If he takes one pace forward praise & treat him
It might take a while or he could pick up the treat idea & the reward of the lead quite quickly The same applies to the lift. TBH I've always carried puppies in lifts(whilst they were small enough to be carried)it can be quite scary moving up & down instead of the natural walking movement