Venial sins are forgiven when one blesses themselves with holy water, confesses them to God directly (we can do this for venial sins), receive communion, etc. There's a lot of ways to get rid of them.
And a plenary indulgence is actually not easy to get because of the requirements:
First, you must do whatever it is. Since most things that gain these indulgences are now common acts of piety and devotion (another includes doing the Stations of the Cross in a church - I know people who do this every day), the actual thing is meeting the other conditions, all of which but one are easy to accomplish as a good Catholic anyway.
The other requirements are making a good Confession (good thing every Catholic should do frequently anyways), receiving Holy Communion (another good thing we should want to do and do frequently), pray for the Pope and his intentions (an Our Father, Hail Mary and Gloria Patri suffice--again, it's always a good thing to pray for the Pope) and you must do this with a spirit of detachment from all sin. That last part is the hard part. That's what makes most indulgences partial.
Still, a rigorous prayer and sacramental life are what help strengthen us as we run towards our goal in Jesus Christ, so doing these things are good anyways, whether we're looking to get purgatory points or not (I'd prefer to get all the purgatory points I can, thanks, I have a feeling I desperately need them as Jesus has a LOT of work to do on me (because it's really all HIM)!