When introducing lifting, consider the suitability of the players for each role.
It may be that a small, light player now takes up a key role in jumping and catching while the bigger players, who may have previously jumped are best suited to lifting at this stage in development
When introducing lifting to young players, always side on caution and use spotters to assist in the initial learning stages. This will develop confidence and competence
Always be aware of fatigue and do not over work the players even if progress is slow